The P0314 OBD-II trouble code means the engine control module has detected a misfire affecting one cylinder but cannot reliably determine which cylinder is responsible.

The generic definition is:

P0314 — Single-Cylinder Misfire, Cylinder Not Specified

P0314 is different from a cylinder-specific code such as P0301 or P0308. Those codes identify the affected cylinder directly. P0314 tells you that one cylinder is weak, but the computer has not supplied its number.

It is also different from P0300, which normally indicates random or multiple-cylinder misfires.

Diagnosing P0314 requires identifying the weak cylinder before testing its spark plug, ignition coil, injector, wiring, compression, and valvetrain operation.

The computer has narrowed the problem to one cylinder. It has simply declined to mention which one, because apparently vehicle diagnostics needed a mystery category.

P0314 belongs to the misfire-code family covered in the complete Pro Street P-code OBD-II guide.

P0314 Quick Answer

Item	Information
Trouble code	P0314
Definition	Single-Cylinder Misfire, Cylinder Not Specified
System	Ignition and combustion
Severity	High
Safe to drive?	Only briefly if the engine runs smoothly and the Check Engine Light is not flashing
Main diagnostic challenge	Identifying which cylinder is misfiring
Best diagnostic tools	Enhanced scan tool, Mode $06 data, power-balance test and relative compression test
Common causes	Spark plug, ignition coil, injector, wiring, intake leak, or low compression
Related codes	P0300, P0301–P0312, P0315 and P0335
Typical repair range	Approximately $50 to $6,000+, depending on the cause

What Does P0314 Mean?

Modern engine computers commonly detect misfires by monitoring changes in crankshaft speed.

Each cylinder accelerates the crankshaft slightly when combustion pushes its piston downward. When one cylinder produces less torque, the crankshaft slows during that cylinder’s expected contribution window.

The computer then compares the crankshaft-speed variation with:

Crankshaft position
Camshaft position
Engine speed
Engine load
Ignition timing
Fuel-injection timing
Known cylinder firing order

If the control module recognizes a consistent single-cylinder combustion loss but cannot confidently assign it to a numbered cylinder, it may store P0314.

The exact enabling conditions vary by manufacturer.

P0314 does not prove that the ignition coil has failed. It only reports that one cylinder is misfiring and has not been identified.

Possible causes include:

Worn spark plug
Weak ignition coil
Damaged plug wire or coil boot
Restricted fuel injector
Injector or coil wiring fault
Localized intake leak
Low compression
Valve problem
Crankshaft signal problem
Incorrect crankshaft variation calibration

For broader information about combustion failures, visit our engine misfire symptoms, causes and diagnosis guide.

P0314 Versus P0300

P0314 and P0300 can create similar drivability problems, but they describe different misfire patterns.

Code	Meaning
P0300	Random or multiple-cylinder misfire detected
P0314	One cylinder is misfiring, but its number has not been identified

A P0300 may indicate:

Several cylinders misfiring
A misfire moving between cylinders
Fuel-pressure failure
Large vacuum leak
Contaminated fuel
Incorrect mechanical timing
Multiple worn ignition components

P0314 indicates that the computer believes the fault is concentrated in one cylinder but cannot assign a cylinder-specific code.

If P0314 and P0300 appear together, review enhanced misfire data carefully. One weak cylinder may be producing enough irregular crankshaft movement to trigger both codes.

P0314 Versus P0301 Through P0312

P0301 through P0312 identify numbered cylinders.

Examples include:

P0314 does not provide that cylinder number.

The diagnostic sequence must therefore begin with locating the weak cylinder. Replacing a component before identifying the cylinder is not diagnosis. It is automotive hide-and-seek with a debit card.

Common Conditions Associated With P0314

A vehicle with P0314 may experience:

Illuminated Check Engine Light
Flashing Check Engine Light
Rough idle
Engine shaking
Uneven exhaust sound
Hesitation
Reduced acceleration
Loss of power
Hard starting
Stalling
Increased fuel consumption
Raw fuel smell from the exhaust
Failed emissions test
Popping from the intake or exhaust
Reduced turbocharger boost
Limp mode

The problem may occur:

Only during cold starts
Only after the engine warms
At idle
During acceleration
Under boost
During wet weather
After an engine repair
Intermittently without obvious symptoms

Freeze-frame data and Mode $06 results can help determine when the misfire becomes active.

How Serious Is P0314?

P0314 should be treated as a high-priority trouble code.

An active misfire may allow unburned fuel to enter the exhaust. That fuel can ignite inside the catalytic converter, causing the catalyst to overheat or melt.

Continued driving may contribute to:

Catalytic converter damage
Oxygen sensor contamination
Cylinder-wall fuel wash
Engine oil dilution
Burned exhaust valves
Piston damage
Excessive vibration
Reduced fuel economy
Increased emissions

Stop Driving Immediately If:

The Check Engine Light is flashing
The engine shakes violently
Power loss becomes severe
The vehicle stalls
A strong raw-fuel smell is present
The engine overheats
Mechanical knocking is heard
Abnormal valvetrain noise develops

A flashing Check Engine Light generally indicates a catalyst-damaging misfire. Reduce engine load, pull over safely, and shut off the engine.

Most Common Causes of P0314

Possible cause	Relative likelihood
Worn or fouled spark plug	Very high
Weak or failed ignition coil	Very high
Damaged plug wire or coil boot	High
Restricted or failed fuel injector	High
Coil or injector wiring fault	Medium
Localized intake leak	Medium
Low compression	Medium
Burned or leaking valve	Medium
Incorrect valve clearance	Application dependent
Carbon buildup on an intake valve	Medium on direct-injected engines
Failed lifter, follower or camshaft lobe	Application dependent
Crankshaft position signal fault	Lower
Damaged reluctor wheel	Lower
Crankshaft variation relearn required	Application dependent
PCM failure	Rare

The first objective is not replacing one of these components. It is determining which cylinder requires testing.

How to Diagnose P0314

Step 1: Confirm P0314

Connect an OBD-II scanner and record:

Stored codes
Pending codes
Permanent codes
Freeze-frame data
Manufacturer-specific codes
Individual-cylinder misfire counters
Mode $06 test results

Do not clear P0314 before saving the diagnostic information.

Record:

Engine RPM
Engine load
Vehicle speed
Coolant temperature
Intake-air temperature
Short-term fuel trim
Long-term fuel trim
Throttle position
Fuel-system status

The freeze-frame data identifies the conditions under which the computer detected the unidentified cylinder misfire.

Step 2: Check for Related Codes

P0314 may appear with:

P0300 — Random or Multiple Cylinder Misfire
P0301–P0312 — Numbered-cylinder misfire codes
P0315 — Crankshaft Position System Variation Not Learned
P0335–P0339 — Crankshaft Position Sensor codes
P0340–P0349 — Camshaft Position Sensor codes
P0171 or P0174 — Lean-condition codes
P0172 or P0175 — Rich-condition codes
P0201–P0212 — Injector circuit codes
P0351–P0362 — Ignition-coil circuit codes

Companion codes may identify the affected cylinder or underlying system.

For example:

Code combination	Diagnostic direction
P0314 only	Identify the weak cylinder using enhanced data and contribution testing
P0314 plus P0302	Begin diagnosis with Cylinder 2
P0314 plus injector circuit code	Test the corresponding injector and circuit
P0314 plus ignition-coil circuit code	Test the corresponding coil and circuit
P0314 plus P0315	Verify crankshaft variation calibration
P0314 plus crankshaft sensor code	Inspect crankshaft signal and reluctor system
P0314 plus lean codes	Check intake leaks, fuel pressure and injector delivery

Step 3: Review Individual-Cylinder Misfire Counters

A professional scan tool may display misfire counts for each cylinder even when the PCM has not set a numbered-cylinder code.

Monitor the counters:

At cold start
During warm idle
At approximately 2,000–2,500 RPM
Under moderate load
During the conditions shown in freeze-frame data

Look for one cylinder accumulating significantly more misfires than the others.

A small number of historical counts may not indicate an active failure. Concentrate on the cylinder that consistently gains counts while the engine is running poorly.

Step 4: Review Mode $06 Data

Mode $06 provides results from onboard monitoring tests. On many vehicles, it can reveal cylinder-specific misfire data before a dedicated P0301–P0312 code is stored.

Mode $06 may display:

Test identification
Component identification
Current test value
Minimum limit
Maximum limit
Pass or fail status

Manufacturer definitions and data formats vary. Some scanners translate the information into named cylinders, while others display hexadecimal test and component identifiers.

Use manufacturer-specific reference information to interpret Mode $06 correctly.

Do not assume the same test ID represents the same cylinder on every vehicle. Standardization occasionally takes a coffee break.

Step 5: Use a Scan-Tool Power-Balance Test

Some professional scan tools can disable individual cylinders electronically while the engine runs.

The test compares the RPM or torque decrease caused by disabling each cylinder.

A healthy cylinder should produce a noticeable drop when disabled.

A weak cylinder may produce:

Little RPM change
Little torque change
No noticeable change
A smaller contribution than neighboring cylinders

This method can identify the weak cylinder without physically disconnecting coils or injectors.

Follow the manufacturer’s procedure. Some vehicles require specific coolant temperature, transmission position, engine speed, or accessory settings before a power-balance test can run.

Step 6: Perform a Manual Cylinder-Contribution Test Carefully

On some engines, a manual contribution test may be possible by disabling one injector at a time using an approved method.

Avoid manually unplugging ignition coils on running engines unless the manufacturer permits it. Doing so may:

Damage ignition components
Create high-voltage shock risk
Store additional codes
Send unburned fuel into the exhaust
Damage the catalytic converter
Damage control-module drivers

If a manual test is appropriate, disabling fuel injection is generally safer than allowing fuel to enter a cylinder with no spark.

The cylinder that produces the smallest change when disabled is the likely weak cylinder.

Step 7: Perform a Relative Compression Test

A relative compression test compares the current required by the starter as each cylinder reaches its compression stroke.

A low-compression cylinder requires less starter current, producing a lower peak in the waveform.

Relative compression testing may use:

Current clamp and oscilloscope
Battery conductance equipment with compression mode
Professional scan tool
Manufacturer diagnostic software

This test can quickly identify a weak cylinder without removing every spark plug.

It does not provide an exact pressure measurement, but it can show whether one cylinder differs significantly from the rest.

Step 8: Use an Exhaust Temperature Test

A misfiring cylinder may produce a cooler exhaust runner because it releases less combustion heat.

Using an infrared thermometer or thermal camera, compare exhaust-runner temperatures shortly after a cold start.

A noticeably cooler runner may identify the weak cylinder.

Important limitations include:

Exhaust manifold shields
Shared manifold passages
Unequal runner lengths
Catalytic converter proximity
Limited access
Surface-emissivity differences

Use temperature comparison as supporting evidence, not the sole diagnosis.

Avoid contact with hot exhaust components. Burns are an inefficient way to confirm that combustion creates heat.

Step 9: Use a Lab Scope to Identify the Weak Cylinder

An oscilloscope can compare:

Ignition primary patterns
Ignition secondary patterns
Injector current ramps
Injector voltage waveforms
Crankshaft acceleration
Camshaft synchronization
Relative compression
Cylinder contribution

Advanced waveform analysis may identify:

Excessive ignition firing voltage
Short spark duration
Weak coil output
Injector pintle movement problems
Missing injector control
Low compression
Reluctor-wheel irregularities

This approach is particularly useful when P0314 is intermittent and no cylinder-specific code is stored.

After Identifying the Cylinder

Once the weak cylinder has been identified, continue with targeted testing.

Step 10: Inspect the Spark Plug

Remove the suspected cylinder’s spark plug and compare it with plugs from healthy cylinders.

Check for:

Worn electrodes
Excessive gap
Cracked porcelain
Carbon fouling
Fuel contamination
Oil deposits
Coolant deposits
Overheating
Incorrect heat range
Wrong plug type

A wet plug may indicate that fuel is entering the cylinder without being ignited.

A dry plug may suggest insufficient fuel delivery.

If the plugs are beyond their service interval, replace the complete set with the correct type and gap.

Step 11: Swap the Ignition Coil

If the engine uses coil-on-plug ignition, move the suspected coil to a known-good cylinder.

Clear the codes and monitor misfire counters again.

If the misfire moves with the coil, the coil is likely defective.

If the misfire remains on the original cylinder, continue testing.

Inspect the coil and boot for:

Carbon tracking
Cracks
Moisture
Oil contamination
Corrosion
Damaged internal contacts
Burned connector terminals

Review our bad ignition coil guide for general ignition-system information.

Also see our ignition coil replacement guide before installing replacement parts.

Step 12: Test the Fuel Injector

A restricted, leaking, stuck, electrically open, or unpowered injector can cause a one-cylinder misfire.

Injector diagnosis may include:

Listening for consistent operation
Resistance testing
Voltage testing
Noid-light testing
Current-ramp testing
Injector balance testing
Fuel-pressure drop testing
Injector swap testing where practical

Useful Pro Street references include:

Use manufacturer resistance and circuit specifications.

Step 13: Inspect the Coil and Injector Circuits

If the coil and injector test correctly, inspect their electrical circuits.

Check for:

Correct supply voltage
Reliable ground
Ignition-coil trigger signal
Injector control pulse
Loose terminal tension
Corroded pins
High circuit resistance
Wiring shorted to ground
Wiring shorted to voltage
Heat-damaged insulation
Poor engine or PCM grounds

Perform voltage-drop testing with the circuit operating whenever possible.

A wire may pass a continuity test while failing under load. The multimeter beep remains helpful, but it is not a legally binding character reference.

Step 14: Check for a Localized Intake Leak

An intake leak near one cylinder’s runner can create a localized lean condition.

Inspect:

Intake manifold gasket
Injector seal
Vacuum connections
PCV plumbing
Intake-runner controls
Intake manifold cracks

A smoke test is generally the safest and most effective way to locate an intake leak.

If the engine uses individual intake runners, compare runner operation and manifold sealing around the identified cylinder.

Step 15: Perform a Conventional Compression Test

If ignition, fuel, and electrical tests do not explain the misfire, measure cylinder compression.

Compare the suspected cylinder with the others and follow manufacturer specifications for minimum pressure and allowable variation.

Low compression may result from:

Burned intake valve
Burned exhaust valve
Bent valve
Worn piston rings
Damaged piston
Broken valve spring
Failed lifter or follower
Worn camshaft lobe
Head gasket failure
Cylinder-wall damage
Incorrect valve timing

If compression is low, continue with a cylinder leak-down test.

Step 16: Perform a Cylinder Leak-Down Test

Position the suspected cylinder at top dead center on its compression stroke and introduce regulated compressed air.

Air heard or observed at	Likely fault
Throttle body or intake	Leaking intake valve
Exhaust outlet	Leaking exhaust valve
Oil filler opening	Piston rings or cylinder damage
Cooling system	Head gasket, cylinder head, or block damage
Adjacent cylinder	Head gasket failure between cylinders

Leak-down testing determines where the cylinder loses pressure.

Step 17: Inspect Valve Operation

If compression is low or valvetrain noise is present, inspect valve movement.

Depending on the engine, diagnosis may require:

Removing the valve cover
Comparing rocker-arm movement
Measuring valve lift
Inspecting valve springs
Checking lifters or followers
Inspecting the camshaft
Verifying engine oil pressure
Checking the oil filter for metal debris

Reduced valve lift may indicate a failed lifter, follower, rocker arm, spring, or camshaft lobe.

Check the Crankshaft Misfire Detection System

If no actual cylinder fault can be found, inspect the system used to detect misfires.

Step 18: Inspect the Crankshaft Position Sensor

A damaged or intermittent crankshaft position sensor signal can create false or inaccurate misfire detection.

Inspect:

Sensor connector
Wiring
Power and ground
Sensor mounting
Air gap where adjustable
Heat damage
Oil contamination
Signal waveform

Crankshaft sensor codes such as P0335–P0339 provide additional evidence of a sensor or circuit problem.

Step 19: Inspect the Reluctor Wheel

The crankshaft position sensor reads a toothed reluctor wheel or tone ring.

Possible problems include:

Bent reluctor tooth
Cracked wheel
Loose reluctor
Incorrect installation
Excessive crankshaft end play
Debris on a magnetic sensor
Damage after engine or transmission service

A distorted reluctor signal may cause the PCM to interpret normal crankshaft-speed variation as a misfire or struggle to identify the correct cylinder.

Oscilloscope testing is often the best way to locate an irregular tooth pattern.

Step 20: Check Whether a Crankshaft Variation Relearn Is Required

Some vehicles require a crankshaft position variation relearn after:

Crankshaft sensor replacement
PCM replacement
Engine replacement
Crankshaft replacement
Reluctor-wheel service
Timing-system repair
Certain transmission or flywheel repairs
Loss of learned calibration data

If the relearn has not been completed, the PCM may not accurately distinguish normal crankshaft variation from combustion misfire.

P0315 may also be stored when the variation value has not been learned.

A capable scan tool and manufacturer-specific procedure may be required. Do not perform a relearn until mechanical, ignition, and fuel faults have been addressed.

Teaching the computer around an actual misfire does not repair the engine. It merely gives the computer incorrect homework.

Step 21: Clear P0314 and Confirm the Repair

After repairing the confirmed fault:

Clear stored and pending codes.
Start the engine.
Verify a stable idle.
Monitor individual-cylinder misfire data.
Review Mode $06 results.
Recreate the original freeze-frame conditions when safe.
Complete any required variation relearn.
Complete the required drive cycle.
Scan for pending or permanent codes.

The repair is confirmed when misfire counters remain normal and P0314 does not return.

Common P0314 Repairs and Costs

Repair	Approximate installed cost
Replace spark plugs	$50–$600
Replace one ignition coil	$80–$500
Replace plug wire or coil boot	$30–$300
Clean or replace one injector	$150–$1,200
Repair wiring or connector	$100–$800
Repair localized intake leak	$100–$1,200
Perform crankshaft variation relearn	$100–$300
Replace crankshaft position sensor	$150–$600
Repair reluctor-wheel problem	$500–$3,000+
Repair valve or cylinder head	$1,500–$6,000+
Replace failed lifter or camshaft	$1,500–$7,000+
Replace engine	$4,000–$20,000+

The diagnosis may require more time than a normal cylinder-specific code because P0314 does not identify which cylinder should be tested first.

Common P0314 Diagnostic Mistakes

Treating P0314 as P0300

P0314 indicates one unidentified cylinder. P0300 normally indicates random or multiple-cylinder misfires.

Replacing Random Ignition Coils

Identify the weak cylinder using scan data, Mode $06, contribution testing, or relative compression before replacing components.

Ignoring Mode $06 Data

Mode $06 may identify the cylinder before a dedicated cylinder-specific code is stored.

Manually Disconnecting Coils Without a Safe Procedure

Disabling ignition may create shock risk, additional codes, catalytic converter damage, or control-module damage.

Skipping Relative Compression Testing

A relative compression test can quickly identify a weak mechanical cylinder without removing every spark plug.

Ignoring Injector Balance

An injector can click and have correct resistance while still delivering an incorrect amount of fuel.

Assuming the Crankshaft Sensor Is Bad

A crankshaft signal problem is possible, but ignition, fuel, compression, wiring, and mechanical faults are generally more common.

Performing a Relearn Before Repairing the Misfire

A relearn should not be used to hide an actual combustion failure.

Clearing Freeze-Frame Data Too Early

The operating conditions stored with P0314 may be essential for reproducing the fault.

P0314 Frequently Asked Questions

What does P0314 mean?

P0314 means the PCM detected a single-cylinder misfire but could not reliably identify the cylinder number.

Is P0314 the same as P0300?

No. P0300 normally indicates random or multiple-cylinder misfires. P0314 indicates one unidentified cylinder.

Why doesn’t P0314 identify the cylinder?

The crankshaft-speed pattern may indicate one weak combustion event without providing enough consistent information to assign it to a numbered cylinder.

How do I find the misfiring cylinder?

Use individual-cylinder misfire counters, Mode $06 data, a scan-tool power-balance test, relative compression, exhaust-temperature comparison, or waveform analysis.

Can a bad ignition coil cause P0314?

Yes. A weak coil can cause one cylinder to misfire before the PCM identifies a cylinder-specific code.

Can a fuel injector cause P0314?

Yes. A restricted, leaking, stuck, electrically failed, or unpowered injector can produce a single-cylinder misfire.

Can low compression cause P0314?

Yes. Burned valves, worn rings, piston damage, valvetrain faults, or head gasket failure can weaken one cylinder.

Can a crankshaft position sensor cause P0314?

Yes, although it is less common than an actual combustion problem. A distorted or intermittent crankshaft signal can interfere with misfire identification.

Can a damaged reluctor wheel cause P0314?

Yes. A bent, cracked, loose, or incorrectly installed reluctor wheel may distort crankshaft-speed data.

Does P0314 require a crankshaft variation relearn?

Not always. A relearn may be required after certain sensor, PCM, engine, crankshaft, timing, flywheel, or transmission repairs.

Can I drive with P0314?

Only briefly if the engine runs smoothly and the Check Engine Light remains steady. Stop driving if the light flashes, the engine shakes severely, power drops, or raw fuel can be smelled.

Can P0314 damage the catalytic converter?

Yes. Continued misfiring can send unburned fuel into the exhaust and overheat the converter.

Related OBD-II Codes

P0300 — Random or Multiple Cylinder Misfire
P0301–P0312 — Numbered-Cylinder Misfire Codes
P0313 — Misfire Detected With Low Fuel
P0314 — Single-Cylinder Misfire, Cylinder Not Specified
P0315 — Crankshaft Position System Variation Not Learned
P0335–P0339 — Crankshaft Position Sensor Codes
P0340–P0349 — Camshaft Position Sensor Codes
P0201–P0212 — Injector Circuit Codes
P0351–P0362 — Ignition-Coil Circuit Codes

Explore the Pro Street OBD-II Code Libraries

Use the Pro Street cornerstone pages to find additional diagnostic trouble codes:

P0314 means the computer detected a one-cylinder misfire but could not identify the cylinder number.

Begin with enhanced misfire counters, Mode $06 information, and power-balance or relative-compression testing. Once the weak cylinder has been identified, test its spark plug, ignition coil, injector, wiring, intake runner, compression, and valve operation.

If no genuine cylinder fault can be confirmed, inspect the crankshaft position signal, reluctor wheel, and variation calibration.

The code may not name the cylinder, but that is not permission to replace parts alphabetically until the engine improves.

P0314 Code: Single-Cylinder Misfire Not Identified