If your OBD-II scanner displays P0168, your vehicle’s Engine Control Module (ECM) or Powertrain Control Module (PCM) has detected that the fuel temperature has exceeded the maximum limit programmed by the manufacturer.
The generic OBD-II definition for P0168 is:
Fuel Temperature Too High
Unlike oxygen sensor-related trouble codes, P0168 is associated with the fuel delivery and engine management system. The PCM relies on the fuel temperature sensor to monitor fuel temperature so it can adjust fuel delivery, injection timing, vapor management, and emissions controls.
Fuel temperature becomes especially important on:
- Direct-injection gasoline engines
- Common-rail diesel engines
- Flex-fuel vehicles
- High-pressure fuel systems
- Turbocharged engines
When fuel becomes hotter than expected, its density changes, vapor formation increases, and fuel system performance may suffer. If the PCM detects a fuel temperature above the manufacturer’s allowable range, it stores P0168 and usually illuminates the Check Engine Light.
Common causes include:
- Failed fuel temperature sensor
- Faulty sensor wiring
- Engine overheating
- Restricted fuel return system
- Excessive engine compartment heat
- High-pressure fuel system problems
- PCM faults (rare)
Unlike P0180 through P0184, which indicate electrical faults in the fuel temperature sensor circuit, P0168 specifically indicates that the PCM believes the fuel itself is excessively hot.
What Does the P0168 Code Mean?
Modern vehicles continuously monitor fuel temperature to ensure accurate fuel delivery and emissions control.
As fuel temperature rises:
- Fuel density decreases.
- Vapor formation increases.
- Fuel pressure characteristics change.
- Injector flow characteristics may vary.
- Engine calibration becomes more critical.
The PCM uses information from the fuel temperature sensor to compensate for these changes.
When fuel temperature exceeds manufacturer specifications, the PCM stores P0168.
The code does not automatically mean the fuel temperature sensor has failed.
The PCM may be accurately reporting genuinely excessive fuel temperatures.
How the Fuel Temperature Sensor Works
Most vehicles use a thermistor-type fuel temperature sensor.
A thermistor changes electrical resistance as temperature changes.
Generally:
- Cold fuel = High resistance
- Warm fuel = Lower resistance
- Hot fuel = Lowest resistance
The PCM supplies:
- Reference voltage
- Ground
- Signal monitoring
As fuel temperature changes, the sensor alters the return voltage, allowing the PCM to calculate fuel temperature.
Why Fuel Temperature Matters
Fuel temperature affects several important engine functions.
The PCM uses fuel temperature information for:
- Fuel injector calculations
- Injection timing
- Fuel density compensation
- Vapor control
- Emissions reduction
- Cold-start strategies
- High-load fuel delivery
Keeping fuel within the proper operating range helps maintain engine performance and emissions compliance.
Where Is the Fuel Temperature Sensor Located?
Fuel temperature sensor location varies by manufacturer.
Common locations include:
- Integrated into the fuel rail
- Mounted inside the fuel pressure sensor
- Installed on the high-pressure fuel pump
- Inside the fuel tank module
- Mounted on the fuel supply line
- Combined with a fuel composition sensor on flex-fuel vehicles
Always consult the factory service manual for the exact sensor location on your vehicle.
How the PCM Detects P0168
The PCM continuously monitors:
- Fuel temperature
- Fuel pressure
- Engine coolant temperature
- Intake air temperature
- Ambient temperature
- Fuel system operating conditions
If the reported fuel temperature exceeds the manufacturer’s calibrated limit for a specified amount of time, the PCM stores P0168.
Some manufacturers require multiple drive cycles before permanently illuminating the Check Engine Light.
Can High Fuel Temperature Cause Problems?
Yes.
Excessively hot fuel may contribute to:
- Vapor formation inside fuel lines
- Reduced fuel density
- Hard starting
- Poor hot restart performance
- Reduced fuel delivery
- Increased emissions
- Engine hesitation under certain conditions
Modern returnless fuel systems are especially sensitive because fuel remains in the engine compartment longer than older return-style systems.
Can a Bad Fuel Temperature Sensor Cause P0168?
Absolutely.
A faulty sensor may incorrectly report excessively high fuel temperatures even when the fuel is operating normally.
Typical sensor failures include:
- Internal electrical failure
- Heat damage
- Moisture intrusion
- Sensor drift
- Wiring damage
- Connector corrosion
Sensor testing should always be performed before replacing expensive fuel system components.
Can Engine Heat Cause P0168?
Yes.
High engine compartment temperatures are one of the most common contributors to P0168.
Possible causes include:
- Engine overheating
- Cooling fan failure
- Restricted airflow
- Missing heat shields
- Turbocharger heat soak
- Exhaust heat transfer
- Prolonged idling in hot weather
Under extreme conditions, fuel temperature can legitimately exceed normal operating limits.
P0168 Quick Facts
| Item | Information |
|---|---|
| DTC | P0168 |
| Generic Definition | Fuel Temperature Too High |
| System | Fuel & Engine Management |
| Severity | Moderate |
| Safe to Drive? | Usually, with caution |
| Common Symptoms | Check Engine Light, hard hot starts, hesitation, reduced performance |
| Common Causes | Failed fuel temperature sensor, excessive engine heat, wiring faults, restricted fuel system |
| Typical Repair Cost | $100–900+ |
| Related Codes | P0180, P0181, P0182, P0183, P0184 |
Common Vehicles That Experience P0168
P0168 may appear on vehicles from:
- Ford
- Chevrolet
- GMC
- Dodge
- Ram
- Toyota
- Lexus
- Nissan
- Infiniti
- Volkswagen
- Audi
- BMW
- Mercedes-Benz
- Hyundai
- Kia
The code is especially common on vehicles equipped with direct fuel injection (GDI), common-rail diesel injection, or flex-fuel systems that actively monitor fuel temperature.
What Does P0168 Really Mean?
The wording of P0168 often leads drivers to believe the engine is overheating.
The code does not automatically mean:
- The engine coolant is overheating.
- The fuel pump has failed.
- The injectors are defective.
- The PCM has failed.
Instead, it means the PCM has determined that fuel temperature is higher than expected, either because the fuel is genuinely overheating or because the fuel temperature sensor or its circuit is providing inaccurate information.
The fault may involve:
- Fuel temperature sensor
- Wiring harness
- Electrical connector
- Fuel system heat soak
- Cooling system problems
- Fuel pressure issues
- PCM
Think of P0168 as the PCM saying:
“The fuel in the system appears hotter than it should be. I need the fuel temperature sensor, wiring, cooling system, and fuel system inspected to determine whether the temperature is truly excessive or the sensor is reporting incorrect data.”
Common P0168 Scan Tool Patterns
Monitoring live scan-tool data is one of the fastest ways to diagnose P0168.
Unlike fuel temperature sensor circuit codes such as P0180 through P0184, P0168 indicates the PCM believes the actual fuel temperature has exceeded the manufacturer’s acceptable operating range.
Professional scan tools allow technicians to compare fuel temperature with coolant temperature, intake air temperature, ambient temperature, fuel pressure, and engine operating conditions to determine whether the problem is caused by actual fuel overheating or a faulty sensor.
Pattern 1: Fuel Temperature Much Higher Than Ambient Temperature
The most common scan-tool pattern is:
- Fuel temperature significantly higher than ambient air
- Fuel temperature continues increasing
- Engine operates normally
- Check Engine Light illuminated
Possible causes include:
- Fuel heat soak
- Failed fuel temperature sensor
- Engine compartment overheating
- Restricted fuel circulation
Pattern 2: Fuel Temperature Increases After Hot Soak
Some vehicles only store P0168:
- After shutting the engine off
- During hot restarts
- After extended idling
- In extremely hot weather
Possible causes include:
- Heat soak
- Missing heat shields
- Poor airflow
- Turbocharger heat transfer
- Fuel rail overheating
Pattern 3: Fuel Temperature Does Not Match Other Sensors
Compare:
- Fuel temperature
- Intake air temperature
- Engine coolant temperature
- Ambient temperature
If:
- Fuel temperature is extremely high
- Other temperatures remain normal
The fault may involve:
- Fuel temperature sensor
- Sensor wiring
- Electrical connector
Comparing multiple temperature sensors helps identify sensor faults.
Pattern 4: Fuel Temperature Rises With Engine Load
During acceleration or towing:
- Fuel temperature increases rapidly
- Fuel pressure remains normal
- Coolant temperature may also increase
Possible causes include:
- Excessive engine heat
- Cooling system problems
- Restricted fuel return
- High-pressure fuel system issues
Pattern 5: Fuel Temperature Remains Fixed
Some scan tools show:
- Fuel temperature fixed at one value
- No change during warm-up
- No response to operating conditions
Possible causes include:
- Failed fuel temperature sensor
- Wiring fault
- Open circuit
- PCM interpretation error
A healthy sensor should display gradual temperature changes.
Pattern 6: Fuel Temperature High With No Other Fuel System Codes
Some vehicles store only:
- P0168
without:
- P0180
- P0181
- P0182
- P0183
- P0184
This usually indicates:
- Genuine fuel overheating
- Sensor calibration drift
- Early sensor failure
- Localized engine compartment heat
Common Symptoms of P0168
The severity of symptoms depends on whether fuel temperature is actually excessive or the sensor is reporting inaccurate information.
Common symptoms include:
- Check Engine Light
- Hard hot starts
- Extended cranking
- Engine hesitation
- Reduced performance
- Hot restart problems
- Reduced fuel economy
- Increased emissions
- Occasional rough idle
- Vapor lock on older fuel systems
Some vehicles exhibit no noticeable drivability symptoms beyond the Check Engine Light.
Check Engine Light
The Check Engine Light is usually the first symptom.
Most manufacturers require:
- Excessive fuel temperature
- Proper operating conditions
- One or more failed self-tests
before storing P0168.
Hard Hot Starts
Excessively hot fuel can increase vapor formation.
This may result in:
- Longer crank times
- Hard restarts
- Temporary rough idle
- Poor hot-start performance
These symptoms are more common in extremely hot climates.
Reduced Engine Performance
In some vehicles, the PCM may adjust fuel delivery when excessive fuel temperature is detected.
Possible symptoms include:
- Reduced acceleration
- Minor hesitation
- Reduced engine response
- Temporary power loss
Most vehicles experience only mild performance changes.
Reduced Fuel Economy
Higher fuel temperatures may slightly reduce:
- Fuel density
- Injector efficiency
- Combustion consistency
Fuel economy changes are usually minor.
Is P0168 Serious?
P0168 is generally considered a moderate severity diagnostic trouble code.
The vehicle is usually safe to drive.
However, prolonged operation with excessively high fuel temperatures may contribute to:
- Reduced fuel system efficiency
- Hard starting
- Increased emissions
- Additional fuel system wear
Repairs should be completed promptly.
Can You Drive With P0168?
Usually, yes.
Driving is generally safe if:
- The engine is not overheating.
- No severe drivability symptoms are present.
- The Check Engine Light is not flashing.
Repairs should be scheduled immediately if:
- Engine overheating occurs.
- Hard starting worsens.
- Fuel pressure problems develop.
- Multiple fuel system codes appear.
P0168 vs Related Trouble Codes
Understanding related fuel temperature codes simplifies diagnosis.
P0168
Fuel Temperature Too High
The PCM detects fuel temperature exceeding manufacturer specifications.
P0180
Fuel Temperature Sensor “A” Circuit Malfunction
General electrical problem affecting the fuel temperature sensor circuit.
P0181
Fuel Temperature Sensor “A” Range/Performance
The sensor operates outside expected performance limits.
P0182
Fuel Temperature Sensor “A” Circuit Low Input
The PCM receives a lower-than-expected voltage signal.
P0183
Fuel Temperature Sensor “A” Circuit High Input
The PCM receives a higher-than-expected voltage signal.
P0184
Fuel Temperature Sensor “A” Circuit Intermittent
The fuel temperature sensor signal becomes intermittent or unstable.
30 Common Causes of P0168
The most common causes include:
- Failed fuel temperature sensor
- Fuel temperature sensor drift
- Engine compartment heat soak
- Engine overheating
- Cooling fan failure
- Low coolant level
- Restricted radiator airflow
- Missing heat shields
- Turbocharger heat transfer
- Exhaust heat affecting fuel lines
- Restricted fuel return system
- High-pressure fuel pump problems
- Fuel rail overheating
- Faulty fuel pressure regulator
- Damaged sensor wiring
- Connector corrosion
- Loose electrical connector
- Open circuit
- Short circuit
- Poor ground connection
- High circuit resistance
- Low battery voltage
- Charging system problems
- Contaminated fuel
- Low fuel level causing excess heat
- Faulty fuel composition sensor (flex-fuel vehicles)
- PCM software issue
- Internal PCM fault
- Low-quality aftermarket sensor
- PCM failure (rare)
Final Thoughts
The P0168 Fuel Temperature Too High code indicates the PCM has detected that fuel temperature has exceeded the manufacturer’s expected operating range. While actual fuel overheating is possible, a faulty fuel temperature sensor, damaged wiring, cooling system problems, heat soak, restricted fuel flow, or electrical faults are often responsible.
Proper diagnosis should determine whether the fault originates in:
- Fuel temperature sensor
- Sensor wiring
- Electrical connector
- Cooling system
- Fuel delivery system
- Engine compartment heat management
- PCM
The next section of this guide covers:
- Complete diagnostic procedures
- Live-data analysis
- Fuel temperature sensor testing
- Cooling system inspection
- Fuel system testing
- Repair procedures
- Repair costs
- Manufacturer-specific troubleshooting
Following a structured diagnostic process prevents unnecessary parts replacement while restoring accurate fuel temperature monitoring and proper engine performance.
Related Pro Street Diagnostic Guides
- P0180 – Fuel Temperature Sensor “A” Circuit Malfunction
- P0181 – Fuel Temperature Sensor “A” Range/Performance
- P0182 – Fuel Temperature Sensor “A” Circuit Low Input
- P0183 – Fuel Temperature Sensor “A” Circuit High Input
- P0184 – Fuel Temperature Sensor “A” Circuit Intermittent
- P0117 – Engine Coolant Temperature Circuit Low Input
How to Diagnose the P0168 Code
Diagnosing P0168 requires determining whether the fuel is actually overheating or whether the fuel temperature sensor is reporting incorrect information.
Unlike P0180 through P0184, which indicate electrical faults or performance issues within the fuel temperature sensor circuit, P0168 indicates the PCM believes the measured fuel temperature itself is excessively high.
The condition may be caused by:
- Failed fuel temperature sensor
- Sensor calibration drift
- Damaged wiring
- Engine overheating
- Fuel system heat soak
- Restricted fuel flow
- Cooling system problems
- PCM issues (rare)
Proper diagnosis should determine whether the problem originates in the fuel temperature sensor, fuel delivery system, cooling system, wiring, or PCM before replacing expensive components.
Safety Precautions
Before beginning diagnosis:
- Park the vehicle on level ground.
- Set the parking brake.
- Wear safety glasses.
- Wear fuel-resistant gloves.
- Work in a well-ventilated area.
- Keep open flames and sparks away from the vehicle.
- Relieve fuel system pressure before disconnecting fuel components.
Modern gasoline direct-injection and common-rail diesel systems may operate at thousands of PSI, making proper safety procedures critical.
Tools Required
Professional diagnosis may require:
- Professional scan tool
- Live-data capability
- Digital multimeter
- Infrared thermometer
- Fuel pressure gauge (where applicable)
- Wiring diagrams
- Back-probe test leads
- Cooling system pressure tester
- Smoke machine (optional)
- Basic hand tools
An infrared thermometer is useful for comparing actual fuel rail temperatures with scan-tool readings.
Step 1 – Verify the Code
Connect a professional scan tool.
Record:
- Stored DTCs
- Pending DTCs
- Permanent DTCs
- Freeze-frame data
Monitor:
- Fuel temperature
- Engine coolant temperature
- Intake air temperature
- Ambient air temperature
- Battery voltage
Always save freeze-frame information before clearing any diagnostic trouble codes.
Step 2 – Check for Related Trouble Codes
P0168 commonly appears with:
- P0180
- P0181
- P0182
- P0183
- P0184
- P0128
- P0217
- P0087
- P0088
Related codes often simplify diagnosis.
| Code Combination | Likely Diagnosis |
|---|---|
| P0168 only | Actual high fuel temperature or sensor error |
| P0168 + P0180 | Fuel temperature sensor circuit fault |
| P0168 + P0181 | Sensor performance problem |
| P0168 + P0217 | Engine overheating affecting fuel temperature |
| P0168 + P0087 | Fuel delivery concern |
Repair related faults before replacing expensive fuel system components.
Step 3 – Monitor Live Fuel Temperature Data
Allow the engine to reach operating temperature.
Observe:
- Fuel temperature
- Coolant temperature
- Intake air temperature
- Ambient temperature
Normal operation:
- Fuel temperature gradually increases
- Temperature remains within manufacturer specifications
- Values change smoothly
Abnormal operation:
- Extremely high fuel temperature
- Sudden temperature spikes
- Temperature frozen at one value
- Unrealistic temperature compared to surrounding components
Large differences between scan data and actual temperatures indicate additional testing is needed.
Step 4 – Compare Fuel Temperature to Actual Temperature
Using an infrared thermometer:
Measure:
- Fuel rail temperature
- Fuel line temperature
- High-pressure pump temperature
Compare those readings with the scan tool.
If scan-tool data differs significantly from measured temperatures, suspect:
- Faulty fuel temperature sensor
- Wiring problem
- Sensor calibration error
Step 5 – Inspect the Fuel Temperature Sensor
Inspect the sensor for:
- Physical damage
- Fuel contamination
- Loose installation
- Heat damage
- Cracked housing
- Fuel leakage
A damaged sensor can falsely report excessively high fuel temperatures.
Step 6 – Inspect the Electrical Connector
Disconnect the sensor connector.
Inspect for:
- Corrosion
- Bent terminals
- Loose pins
- Moisture intrusion
- Broken locking tabs
- Fuel contamination
Poor electrical connections frequently distort sensor readings.
Step 7 – Inspect the Wiring Harness
Inspect wiring between the sensor and PCM.
Look for:
- Chafed insulation
- Melted wiring
- Exhaust heat damage
- Pinched wires
- Rodent damage
- Previous repair damage
Heat damage is especially common near turbochargers and exhaust manifolds.
Step 8 – Test Sensor Voltage
Using a digital multimeter:
Verify:
- Reference voltage
- Sensor ground
- Signal voltage
Compare measured values with manufacturer specifications.
Incorrect voltage readings may indicate wiring or PCM faults.
Step 9 – Test Sensor Resistance
Disconnect the fuel temperature sensor.
Measure resistance.
Compare resistance at known temperatures using the manufacturer’s resistance chart.
If resistance does not change appropriately with temperature, replace the sensor.
Step 10 – Inspect the Cooling System
Since excessive engine heat can raise fuel temperature:
Inspect:
- Coolant level
- Radiator condition
- Cooling fan operation
- Thermostat operation
- Water pump performance
- Radiator airflow
Correct cooling system problems before replacing fuel system components.
Step 11 – Inspect for Fuel Heat Soak
Inspect for:
- Missing heat shields
- Exhaust proximity
- Turbocharger heat transfer
- Restricted airflow
- Fuel rail insulation damage
Excessive heat soak can legitimately raise fuel temperature after shutdown or extended idling.
Step 12 – Inspect the Fuel Delivery System
Inspect:
- Fuel pump
- Fuel pressure
- Fuel return system (if equipped)
- Fuel filter
- Fuel rail
Restricted fuel circulation can increase fuel temperature.
Step 13 – Review Technical Service Bulletins
Before replacing expensive components:
Review manufacturer Technical Service Bulletins (TSBs).
Look for updates involving:
- Fuel temperature sensor calibration
- PCM software
- Fuel rail heat management
- Wiring revisions
Some manufacturers have released updated calibrations for false P0168 detection.
Step 14 – Review Freeze-Frame Data
Compare current operating conditions with freeze-frame information.
Review:
- Engine load
- Coolant temperature
- Vehicle speed
- Fuel temperature
- Intake air temperature
- Ambient temperature
Freeze-frame data often identifies exactly when excessive fuel temperature occurred.
Step 15 – Inspect PCM Connector Integrity
Inspect PCM connectors for:
- Corrosion
- Loose pins
- Moisture intrusion
- Damaged terminals
- Bent connectors
Poor PCM connections may distort fuel temperature sensor readings.
Step 16 – Verify Charging System Voltage
Measure charging voltage.
Normal charging voltage should remain between:
- 13.5–14.8 volts
Electrical system problems can interfere with accurate sensor operation.
Step 17 – Inspect Previous Repairs
Inspect for:
- Incorrect replacement sensor
- Low-quality aftermarket components
- Poor wiring repairs
- Harness rerouting
- Fuel system modifications
Improper repairs frequently create inaccurate sensor readings.
Step 18 – Verify Fuel Pressure
Measure fuel pressure using the proper procedure.
Compare readings with manufacturer specifications.
Fuel pressure abnormalities may contribute to excessive fuel temperatures.
Step 19 – Verify Sensor Operation During Road Test
Monitor live data while driving.
Observe:
- Fuel temperature
- Engine load
- Coolant temperature
- Intake air temperature
Fuel temperature should rise gradually without sudden spikes or unrealistic values.
Step 20 – Confirm the Diagnosis
Before replacing any major component, verify:
- Fuel temperature sensor accuracy
- Sensor resistance
- Wiring continuity
- Connector integrity
- Cooling system operation
- Fuel delivery system performance
- Charging system voltage
- PCM software level
Completing these diagnostic steps prevents unnecessary parts replacement while accurately identifying the root cause of P0168.
Step 21 – Replace the Fuel Temperature Sensor
If testing confirms the fuel temperature sensor is reporting incorrect values or has failed internally, replacement is the proper repair.
General replacement procedure:
- Relieve fuel system pressure according to the manufacturer’s procedure.
- Disconnect the negative battery cable.
- Disconnect the electrical connector from the sensor.
- Remove the sensor from the fuel rail, fuel line, fuel pump module, or fuel composition sensor assembly (depending on vehicle design).
- Inspect the sealing surfaces and O-rings.
- Install an OEM or high-quality replacement sensor.
- Reconnect the electrical connector.
- Restore fuel system pressure.
- Clear all diagnostic trouble codes.
- Verify proper sensor operation using a professional scan tool.
OEM sensors generally provide more accurate temperature readings and longer service life than low-cost aftermarket replacements.
Step 22 – Repair Damaged Wiring
Inspect the complete fuel temperature sensor wiring harness.
Repair:
- Broken wires
- Chafed insulation
- Melted wiring
- Pinched harnesses
- High-resistance wiring
- Damaged wire splices
Heat from the engine, turbocharger, or exhaust system frequently damages nearby wiring.
Step 23 – Repair Connector Problems
Inspect the fuel temperature sensor connector.
Repair or replace:
- Corroded terminals
- Bent connector pins
- Loose terminals
- Moisture-damaged connectors
- Fuel-contaminated connectors
- Broken locking tabs
Poor electrical connections can cause inaccurate fuel temperature readings.
Step 24 – Repair Ground Circuit Problems
Inspect:
- Engine grounds
- Chassis grounds
- Sensor ground circuit
- Ground eyelets
Measure:
- Ground resistance
- Voltage drop under load
Poor grounds may distort sensor voltage and cause false high-temperature readings.
Step 25 – Repair Cooling System Problems
If excessive engine heat is contributing to high fuel temperatures, inspect and repair:
- Low coolant level
- Thermostat failure
- Cooling fan malfunction
- Water pump failure
- Restricted radiator
- Damaged radiator cap
- Air trapped in the cooling system
Correcting engine overheating often eliminates P0168.
Step 26 – Repair Fuel System Heat Soak Problems
Inspect for:
- Missing heat shields
- Damaged fuel line insulation
- Exhaust components contacting fuel lines
- Turbocharger heat exposure
- Poor engine compartment airflow
Installing missing heat shields or repairing damaged insulation may significantly reduce fuel temperatures.
Step 27 – Repair Fuel Delivery Problems
Inspect the complete fuel system.
Repair:
- Restricted fuel filters
- Faulty fuel pressure regulators
- Weak fuel pumps
- Restricted return lines (where equipped)
- Damaged fuel rails
Restricted fuel circulation can increase fuel temperature under heavy load.
Step 28 – Update PCM Software
Before replacing the PCM:
Review manufacturer Technical Service Bulletins (TSBs).
Manufacturers occasionally release software updates addressing:
- False P0168 detection
- Fuel temperature calibration
- Fuel system monitoring logic
- PCM operating strategies
- Sensor calibration improvements
Always verify the PCM contains the latest available calibration.
Step 29 – Verify Fuel Temperature Operation
After repairs:
Monitor:
- Fuel temperature
- Coolant temperature
- Intake air temperature
- Fuel pressure
Verify:
- Fuel temperature changes smoothly.
- No unrealistic spikes occur.
- Sensor readings closely match actual operating conditions.
Complete a full drive cycle to confirm the repair.
Step 30 – Consider PCM Failure
PCM failure is extremely uncommon.
Only suspect the PCM after confirming:
- Fuel temperature sensor accuracy
- Wiring continuity
- Connector integrity
- Ground quality
- Cooling system operation
- Fuel delivery system operation
- Charging system voltage
- PCM software updates
PCM replacement should always be the final diagnostic step.
How to Fix P0168
The proper repair depends entirely on the diagnostic results.
Common repairs include:
- Replacing the fuel temperature sensor
- Repairing damaged wiring
- Replacing damaged connectors
- Repairing poor grounds
- Repairing cooling system faults
- Restoring proper fuel circulation
- Installing missing heat shields
- Repairing engine overheating problems
- Updating PCM software
- Replacing the PCM (rare)
Verifying the Repair
After completing repairs:
- Clear all diagnostic trouble codes.
- Start the engine.
- Allow the engine to reach operating temperature.
- Monitor live fuel temperature data.
- Compare fuel temperature with coolant and intake air temperatures.
- Complete a full drive cycle.
- Confirm no pending or permanent DTCs return.
- Perform a final scan to verify a successful repair.
A successful repair restores accurate fuel temperature monitoring, proper fuel system operation, normal emissions performance, and prevents the P0168 code from returning.
Typical Repair Costs
| Repair | Typical Cost |
|---|---|
| Professional diagnosis | $100–250 |
| Fuel temperature sensor replacement | $150–450 |
| Wiring repair | $100–400 |
| Connector replacement | $100–300 |
| Ground circuit repair | $100–250 |
| Cooling system repair | $150–1,500+ |
| Fuel pump replacement | $400–1,500 |
| Fuel pressure regulator replacement | $200–700 |
| Fuel filter replacement | $100–300 |
| Heat shield replacement | $100–500 |
| PCM software update | $100–250 |
| PCM replacement | $800–2,000+ |
Repair costs vary depending on vehicle design, labor rates, fuel system configuration, and the underlying cause of the excessive fuel temperature.
Common Diagnostic Mistakes
Avoid these common mistakes:
- Replacing the fuel temperature sensor before verifying actual fuel temperature
- Ignoring engine overheating
- Failing to compare scan-tool data with an infrared thermometer
- Overlooking damaged heat shields
- Ignoring wiring damage near the exhaust
- Clearing codes before recording freeze-frame data
- Ignoring Technical Service Bulletins
- Replacing the fuel pump before verifying fuel pressure
- Replacing the PCM before verifying the complete electrical system
Many P0168 repairs involve correcting cooling system problems or sensor issues rather than replacing major fuel system components.
Manufacturer-Specific Notes
Ford
Inspect:
- Fuel rail temperature
- Cooling fan operation
- Fuel temperature sensor wiring
- PCM calibration
Heat soak is a common contributor to P0168 on EcoBoost applications.
General Motors (Chevrolet/GMC)
Verify:
- Fuel temperature sensor readings
- Fuel pressure
- Wiring continuity
- Cooling system performance
Direct-injection engines are particularly sensitive to fuel temperature changes.
Toyota/Lexus
Inspect:
- Fuel temperature sensor accuracy
- Cooling system efficiency
- Harness routing
- PCM software updates
Factory scan tools provide enhanced fuel temperature diagnostics.
Honda/Acura
Inspect:
- Fuel rail heat exposure
- Sensor connector condition
- Wiring integrity
- Engine cooling performance
Engine compartment heat can affect sensor readings on turbocharged models.
Nissan/Infiniti
Verify:
- Fuel temperature data
- Fuel pressure
- Heat shielding
- Harness condition
Turbocharged engines may experience higher fuel temperatures during prolonged idle periods.
BMW/Mercedes-Benz
Inspect:
- Fuel temperature adaptation values
- Fuel pressure
- Cooling system performance
- Sensor calibration
Factory diagnostic software provides advanced fuel system temperature analysis.
Hyundai/Kia
Inspect:
- Sensor wiring
- Connector corrosion
- Cooling fan operation
- Fuel system routing
Electrical connection problems are common causes of inaccurate fuel temperature readings.
Frequently Asked Questions
What usually fixes P0168?
The most common repairs include replacing the fuel temperature sensor, repairing damaged wiring, correcting cooling system problems, restoring proper fuel circulation, replacing damaged connectors, repairing poor grounds, or updating PCM software.
Can I drive with P0168?
Usually, yes. Most vehicles remain drivable, but repairs should be completed promptly because excessive fuel temperature can reduce performance, increase emissions, and contribute to hard hot starts.
Does P0168 always mean the fuel is actually overheating?
No. A faulty fuel temperature sensor, damaged wiring, connector corrosion, or sensor calibration errors can falsely report excessively high fuel temperatures.
Can engine overheating cause P0168?
Yes. An overheating engine can significantly increase fuel temperature, especially on direct-injection and turbocharged engines where the fuel rail is exposed to high engine compartment temperatures.
Can P0168 cause a failed emissions inspection?
Yes. If the Check Engine Light is illuminated, the vehicle will typically fail an OBD-II emissions inspection until the underlying fault is repaired.
Is P0168 a serious code?
P0168 is generally considered a moderate severity diagnostic trouble code. While it may not immediately affect drivability, prolonged operation with excessive fuel temperatures or inaccurate sensor readings can reduce engine performance, increase emissions, and contribute to fuel system wear.
Final Thoughts
The P0168 Fuel Temperature Too High code indicates the PCM has detected fuel temperatures exceeding the manufacturer’s expected operating range. While actual fuel overheating can occur, faulty fuel temperature sensors, damaged wiring, cooling system problems, heat soak, restricted fuel flow, and electrical faults are often responsible.
A complete diagnosis should always verify:
- Fuel temperature sensor accuracy
- Wiring continuity
- Connector integrity
- Ground quality
- Cooling system operation
- Fuel delivery system performance
- Charging system voltage
- PCM software level
Following a structured diagnostic process prevents unnecessary parts replacement while restoring accurate fuel temperature monitoring, proper fuel delivery, emissions compliance, and reliable engine operation.
Continue Your Pro Street Fuel System Series
Related guides include:
- P0180 – Fuel Temperature Sensor “A” Circuit Malfunction
- P0181 – Fuel Temperature Sensor “A” Range/Performance
- P0182 – Fuel Temperature Sensor “A” Circuit Low Input
- P0183 – Fuel Temperature Sensor “A” Circuit High Input
- P0184 – Fuel Temperature Sensor “A” Circuit Intermittent
- P0217 – Engine Coolant Overtemperature Condition
These guides provide comprehensive coverage of fuel temperature monitoring, cooling system diagnostics, fuel system troubleshooting, and advanced OBD-II repair procedures.
