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P0124 Code Explained: Throttle/Pedal Position Sensor “A” Circuit Intermittent Causes, Symptoms & Fixes

Illustration of an intermittent throttle or accelerator pedal position sensor circuit fault causing the P0124 diagnostic trouble code.

If your OBD-II scanner displays P0124, your vehicle’s Engine Control Module (ECM) or Powertrain Control Module (PCM) has detected an intermittent signal from the Throttle/Pedal Position Sensor “A” circuit.

The generic OBD-II definition for P0124 is:

Throttle/Pedal Position Sensor/Switch “A” Circuit Intermittent

Unlike P0120, which indicates a general circuit malfunction, P0122, which indicates a low-voltage condition, or P0123, which indicates excessive voltage, P0124 tells the PCM that the sensor signal is dropping out, fluctuating, or becoming unstable intermittently.

In other words, the sensor may operate perfectly one moment and then suddenly produce an unexpected signal before returning to normal.

Intermittent electrical faults are among the most frustrating problems to diagnose because the vehicle often behaves normally while it’s sitting in the repair bay.

Depending on the manufacturer, Sensor “A” may refer to:

Because manufacturers use different electronic throttle strategies, P0124 does not always identify the same physical component.

Some vehicles monitor a serviceable throttle position sensor mounted on the throttle shaft.

Others monitor an internal sensor located inside the electronic throttle body.

Many drive-by-wire vehicles use the accelerator pedal assembly itself.

Knowing which component your vehicle calls Sensor “A” is the first step toward an accurate diagnosis.

Replacing the wrong part is an excellent way to make your wallet lighter without making the Check Engine Light disappear.

What Does the P0124 Code Mean?

P0124 indicates that the PCM has detected an intermittent or erratic voltage signal from the primary throttle or accelerator pedal position sensor.

Instead of remaining smooth and predictable, the signal unexpectedly changes, drops out, spikes, or disappears long enough for the PCM to recognize that the circuit is unreliable.

Most throttle-position sensors operate using three primary circuits:

As the throttle plate or accelerator pedal moves, the signal voltage changes smoothly across its operating range.

On many analog systems this commonly ranges between:

Actual values vary depending on:

The important factor is not the exact voltage.

The important factor is that the voltage changes smoothly and consistently.

If the PCM detects:

it stores P0124.

Unlike P0122 or P0123, the signal may return to normal immediately after the fault occurs.

P0124 Quick Facts

ItemInformation
DTCP0124
Generic DefinitionThrottle/Pedal Position Sensor “A” Circuit Intermittent
SystemElectronic Throttle Control
SeverityModerate to High
Safe to Drive?Generally No
Common SymptomsHesitation, intermittent Reduced Engine Power, poor throttle response, surging, Check Engine Light
Common CausesLoose connector, damaged wiring, failing TPS, failing APP sensor, intermittent ground, connector corrosion
Typical Repair Cost$100–$1,200+
Related CodesP0120, P0121, P0122, P0123, P0224, P2135

How the Electronic Throttle System Works

Modern vehicles use Electronic Throttle Control (ETC) instead of a traditional mechanical throttle cable.

When the driver presses the accelerator pedal:

  1. Accelerator Pedal Position sensors measure pedal movement.
  2. The PCM calculates the driver’s torque request.
  3. The PCM commands the electronic throttle motor.
  4. Throttle Position Sensors verify actual throttle angle.
  5. The PCM compares requested and actual throttle positions thousands of times every minute.

Because throttle position directly affects:

the PCM constantly checks that all throttle-related sensors agree with one another.

If one signal suddenly disappears or behaves erratically, the PCM assumes the circuit cannot be trusted.

Why Multiple Position Sensors Are Used

Electronic throttle systems use redundant sensors for safety.

A typical accelerator pedal contains:

A modern electronic throttle body commonly contains:

Rather than trusting one sensor alone, the PCM compares both signals continuously.

Depending on manufacturer design:

The PCM knows exactly how these sensors should relate to one another.

If Sensor “A” suddenly loses its signal, spikes unexpectedly, or fluctuates while Sensor “B” remains stable, the PCM identifies the condition as an intermittent circuit fault and stores P0124.

How a Throttle Position Sensor Works

A throttle-position sensor converts throttle angle into an electrical signal that the PCM can interpret.

Depending on the vehicle, the sensor may use:

Potentiometer Sensors

Older TPS designs use a resistive strip and movable contact.

As the throttle rotates, the contact slides across the resistor.

Wear over time can create:

These failures commonly trigger P0124 before progressing into permanent low- or high-voltage faults.

Hall-Effect Sensors

Many newer systems eliminate mechanical contact.

Hall-effect sensors are generally more reliable but can still fail because of:

Regardless of design, the PCM expects the signal to remain smooth and uninterrupted.

How the Accelerator Pedal Position Sensor Works

On drive-by-wire vehicles, the accelerator pedal itself contains electronic sensors.

Instead of pulling a throttle cable, the pedal reports the driver’s requested acceleration electronically.

The PCM uses this information to control:

If the pedal signal intermittently disappears or fluctuates unexpectedly, the PCM can no longer determine the driver’s true request.

Most manufacturers respond by reducing engine power until reliable information returns.

How the PCM Detects P0124

The PCM continuously evaluates Sensor “A” for smooth, predictable operation.

P0124 may be stored when the PCM detects:

Unlike P0122 or P0123, the voltage itself may be perfectly normal before and after the failure.

The problem is that it fails intermittently, making diagnosis considerably more challenging.

What Does “Circuit Intermittent” Mean?

“Circuit Intermittent” means the electrical signal is not consistently reliable.

The PCM occasionally loses confidence in the signal because it behaves unpredictably.

Common causes include:

Unlike a complete circuit failure, intermittent faults often disappear before a technician begins testing.

That’s why P0124 has earned a reputation for testing patience almost as much as it tests electrical systems.

Common P0124 Scan Tool Patterns

Because P0124 is an intermittent fault, live scan data is often the fastest way to identify the source of the problem.

Unlike P0122 or P0123, the sensor may operate perfectly during one drive and fail only briefly during another.

Using a scan tool capable of graphing live sensor data dramatically improves the chances of finding the fault.

Pattern 1: Sensor A Drops Out Briefly

Live data may show:

Possible causes include:

Pattern 2: Signal Suddenly Spikes

Instead of dropping out, the voltage may suddenly jump.

Possible scan-tool readings include:

Possible causes:

Pattern 3: Sensor A Freezes

The signal stops changing even though the throttle continues moving.

Possible causes:

Pattern 4: Fault Only Appears While Driving

Many P0124 vehicles idle perfectly.

The code only appears during:

This strongly suggests an intermittent electrical connection.

Pattern 5: Harness Movement Reproduces the Fault

Moving the engine harness while watching live data may cause:

This often identifies damaged wiring hidden inside the insulation.

Pattern 6: Multiple Throttle Codes

P0124 may appear with:

When multiple throttle-related codes appear together, inspect the shared wiring and connectors before replacing components.

Common Symptoms of P0124

Symptoms depend on:

Common symptoms include:

The vehicle may drive perfectly for several days before the fault suddenly returns.

Check Engine Light

Most vehicles illuminate the Check Engine Light after the PCM detects repeated signal interruptions.

Additional warnings may include:

Hesitation During Acceleration

One of the earliest symptoms is hesitation.

Because the PCM briefly loses throttle information, acceleration may feel:

Drivers often describe it as if someone briefly lifted off the accelerator.

Intermittent Reduced Engine Power

Unlike permanent throttle faults, P0124 often causes Reduced Engine Power only while the fault is active.

Once the signal returns, the vehicle may temporarily drive normally again.

This intermittent behavior often confuses owners into believing the problem has fixed itself.

Unfortunately, wiring problems rarely heal overnight.

Engine Surging

An unstable throttle signal can cause repeated throttle corrections.

The PCM continually adjusts engine torque while attempting to determine the true throttle position.

Possible symptoms include:

High or Unstable Idle

Intermittent throttle-position data may affect idle calculations.

Possible symptoms include:

Stalling

Some vehicles stall because the PCM briefly loses throttle-position information during idle.

Stalling may occur:

Cruise Control Disabled

Cruise control relies on accurate throttle-position information.

If Sensor “A” becomes unreliable, the PCM typically disables cruise control until repairs are completed.

Transmission Shift Problems

Throttle-position data influences automatic transmission operation.

An intermittent signal may cause:

Transmission symptoms frequently disappear after correcting the throttle fault.

Is P0124 Serious?

Yes.

P0124 should be considered a moderate-to-high severity diagnostic trouble code.

Because the fault directly affects electronic throttle control, drivability can quickly become unpredictable.

Possible consequences include:

Can You Drive With P0124?

Driving with P0124 is generally not recommended.

A short trip may be possible if:

Avoid driving if:

Intermittent electrical faults rarely become more reliable over time.

P0124 vs Related Codes

Understanding related codes helps narrow the diagnosis.

P0120

General Sensor “A” circuit malfunction.

P0121

Sensor performance or range problem.

P0122

Sensor voltage too low.

P0123

Sensor voltage too high.

P0124

Sensor signal becomes intermittent or unstable.

P0224

Throttle/Pedal Position Sensor “B” Circuit Intermittent.

P2135

Sensor A and Sensor B correlation fault.

P0124 often appears before a sensor completely fails and begins setting P0122 or P0123.

30 Common Causes of P0124

The most common causes include:

  1. Loose throttle-body connector
  2. Loose accelerator-pedal connector
  3. Failing throttle-position sensor
  4. Failing accelerator-pedal sensor
  5. Broken signal wire
  6. Broken ground wire
  7. Corroded connector terminals
  8. Moisture intrusion
  9. Oil contamination
  10. Damaged connector locks
  11. Bent connector pins
  12. Weak terminal tension
  13. Harness rubbing on engine components
  14. Heat-damaged wiring
  15. Rodent-damaged wiring
  16. Previous poor wiring repairs
  17. Engine harness movement
  18. Dashboard wiring damage
  19. Aftermarket pedal controller
  20. Remote-start installation
  21. Alarm-system wiring
  22. Shared ground problems
  23. Shared five-volt reference issues
  24. PCM connector corrosion
  25. Battery voltage instability
  26. Charging-system faults
  27. Electronic throttle-body failure
  28. Accelerator pedal assembly failure
  29. PCM software issues
  30. Internal PCM failure (rare)

Final Thoughts

The P0124 Throttle/Pedal Position Sensor “A” Circuit Intermittent code indicates that the PCM has detected an unstable or unreliable throttle-position signal rather than a permanently high or low voltage.

The most common causes include:

Unlike many electrical codes, P0124 often disappears before diagnosis begins, making careful live-data analysis and wiring inspection essential.

The next section of this guide walks through complete diagnostic procedures, including:

Following a systematic diagnostic process helps identify the true intermittent fault before it becomes a permanent one.

How to Diagnose the P0124 Code

Diagnosing P0124 is different from diagnosing P0122 or P0123 because the signal is intermittent rather than consistently high or low.

The throttle or pedal position sensor may operate perfectly while the vehicle is parked, only to fail briefly when:

Finding an intermittent fault requires patience, live data, and a systematic testing process.

The code may involve:

Always verify what the manufacturer identifies as Sensor “A” before replacing components.

P0124 Safety Precautions

Electronic throttle systems can activate unexpectedly.

Before testing:

The throttle plate may move automatically whenever the ignition is switched on.

Tools Needed

A thorough P0124 diagnosis may require:

An intermittent code often requires more than a simple code reader.

Step 1 – Confirm the Code

Connect the scan tool and record:

Do not erase the code until all freeze-frame information has been saved.

Freeze-frame data frequently reveals the conditions under which the fault occurred.

Step 2 – Check for Related Codes

P0124 often appears with:

Related codes help determine whether the fault affects:

Code CombinationLikely Cause
P0124 onlySensor A intermittently failing
P0124 + P2135Sensor disagreement
P0124 + P0224Wiring or shared circuit
Multiple throttle codesHarness or connector problem
P0124 + throttle actuator codesElectronic throttle body

Step 3 – Verify Sensor “A”

Consult factory service information.

Determine:

Different manufacturers assign Sensor “A” differently.

Never assume the code always points to the throttle body.

Step 4 – Check Battery and Charging Voltage

Electronic throttle systems require stable voltage.

Typical readings:

Engine OFF:

Engine RUNNING:

Inspect:

Voltage instability may contribute to intermittent electronic throttle faults.

Step 5 – Perform a Complete Visual Inspection

Inspect:

Look for:

Many intermittent faults are visible before electrical testing begins.

Step 6 – Inspect the Throttle Body Connector

Disconnect the connector.

Inspect:

A connector that appears secure may still contain one loose terminal.

Step 7 – Inspect the Accelerator Pedal Connector

If the vehicle uses the pedal as Sensor “A”, inspect:

Many intermittent pedal faults originate beneath the dashboard.

Step 8 – Observe Live Data

Turn the ignition ON.

Monitor:

Healthy signals should move smoothly with no sudden interruptions.

A brief spike or dropout is enough to trigger P0124.

Step 9 – Graph Sensor Data

Graphing is considerably more useful than watching changing numbers.

Look for:

Intermittent failures are often obvious on a graph.

Step 10 – Slowly Sweep the Accelerator

Slowly depress the accelerator pedal several times.

Repeat:

Watch for:

Repeat the test several times.

Intermittent failures rarely occur on command.

Step 11 – Compare Sensor A With Sensor B

Modern electronic throttle systems constantly compare redundant sensors.

Possible observations:

Sensor A Drops Out

Sensor B remains normal.

Possible causes:

Both Sensors Drop Out

Possible causes:

Pedal Stable — Throttle Drops Out

Likely throttle body issue.

Throttle Stable — Pedal Drops Out

Likely pedal assembly issue.

Step 12 – Wiggle Test the Harness

Monitor live data while gently moving:

Watch for:

A successful wiggle test often identifies intermittent wiring faults within minutes.

Step 13 – Measure Sensor Voltage

Back-probe Sensor A.

Typical analog values:

Closed throttle:

Approximately 0.5 volts

Wide-open throttle:

Approximately 4.5 volts

An intermittent fault may briefly:

Capturing these events often requires multiple attempts.

Step 14 – Verify the Five-Volt Reference

Measure the reference circuit.

Possible readings:

Normal

Approximately five volts.

Continue diagnosis.

Missing

Possible causes:

Unstable

Possible causes:

Intermittent five-volt reference failures frequently affect multiple sensors.

Step 15 – Test Sensor Ground

Inspect the sensor ground using voltage-drop testing.

Check:

High resistance may produce intermittent operation even when continuity appears normal.

Never rely solely on an audible continuity test.

Step 16 – Test the Signal Wire

Disconnect the sensor when appropriate.

Inspect for:

Move the harness while monitoring continuity.

Broken conductors frequently pass stationary tests but fail during movement.

Step 17 – Perform Terminal Tension Testing

Inspect every connector terminal.

Replace terminals that:

Weak terminals are one of the most overlooked causes of intermittent electronic throttle faults.

Step 18 – Use an Oscilloscope

An oscilloscope is the preferred tool for intermittent sensor diagnosis.

A healthy waveform should remain:

Faulty waveforms may show:

Repeat testing while:

Oscilloscopes often reveal faults that multimeters completely miss.

Step 19 – Road Test With Live Data

If the fault only occurs while driving, record live data during a controlled road test.

Monitor:

Compare live data to the freeze-frame conditions.

Attempt to duplicate:

The goal is to reproduce the intermittent failure safely.

Step 20 – Review Freeze-Frame Information

Compare your testing results to the original freeze-frame.

Ask:

Freeze-frame data often points directly toward the operating conditions needed to reproduce an intermittent fault.

Next Section

Part 2B continues with:

Together, Parts 2A and 2B create a complete professional diagnostic and repair guide for the P0124 trouble code.

Step 21 – Test the Accelerator Pedal Position Sensor

If the manufacturer identifies the Accelerator Pedal Position (APP) Sensor as Sensor “A”, evaluate both pedal sensors using live scan data.

Monitor:

Slowly depress the pedal through its full travel several times.

A healthy sensor should produce:

If APP Sensor A intermittently drops out while Sensor B remains stable, inspect:

Many manufacturers require replacement of the complete pedal assembly.

Step 22 – Inspect Pedal Operation

Before replacing the pedal assembly, inspect it for mechanical problems.

Look for:

A binding pedal can occasionally produce abnormal sensor readings.

Step 23 – Test the Electronic Throttle Body

If Sensor “A” is integrated into the throttle body, inspect:

If the throttle motor operates normally while Sensor A intermittently loses its signal, the internal position sensor may be failing.

Step 24 – Perform Bidirectional Testing

Professional scan tools allow electronic throttle control testing.

Command various throttle positions while monitoring:

Possible results include:

Commanded Angle Changes — Actual Angle Does Not

Possible causes:

Actual Angle Changes — Sensor A Drops Out

Possible causes:

Both Sensors Fail Simultaneously

Possible causes:

Step 25 – Compare Throttle Data to MAP and MAF

Throttle position should closely match changes in:

If airflow changes normally while Sensor A intermittently drops out, the airflow system is likely functioning correctly.

Focus diagnosis on the electrical circuit.

Step 26 – Inspect Aftermarket Accessories

Many intermittent throttle faults begin after installation of:

Inspect every aftermarket connection carefully.

Loose adapters frequently trigger intermittent throttle codes.

Step 27 – Review Recent Repairs

Ask whether the vehicle recently received:

Many intermittent wiring faults begin immediately after unrelated repairs.

Step 28 – Check Technical Service Bulletins

Before replacing expensive components, search manufacturer Technical Service Bulletins (TSBs).

Look for bulletins involving:

Factory bulletins often identify known failure points.

Step 29 – Verify PCM Power and Grounds

Inspect:

Poor PCM grounds can create intermittent sensor failures throughout the vehicle.

Step 30 – Test the Circuit at the PCM

If the sensor appears normal, back-probe the PCM connector.

Possible findings:

Normal Voltage at Sensor and PCM

Possible causes:

Correct at Sensor — Incorrect at PCM

Possible causes:

Incorrect at Both Locations

Possible causes:

Step 31 – Consider PCM Software

Some manufacturers have released calibration updates addressing intermittent throttle-position faults.

Programming should always be performed with:

Software updates cannot repair damaged wiring.

Step 32 – Consider PCM Failure

PCM failure is uncommon.

Only consider PCM replacement after verifying:

Replacing the PCM should always be the final step—not the first guess.

How to Fix P0124

The correct repair depends on the diagnostic results.

Common repairs include:

Replacing the Throttle Position Sensor

If the TPS is serviceable separately:

  1. Disconnect the battery if required.
  2. Disconnect the connector.
  3. Remove the mounting screws.
  4. Install the replacement sensor.
  5. Adjust if applicable.
  6. Tighten fasteners.
  7. Reconnect the wiring.
  8. Perform throttle relearn.
  9. Verify live data.

Many modern throttle bodies do not allow separate TPS replacement.

Replacing the Electronic Throttle Body

General procedure:

  1. Disconnect the battery.
  2. Remove the intake duct.
  3. Disconnect electrical connectors.
  4. Remove coolant hoses if equipped.
  5. Remove mounting bolts.
  6. Install a new gasket.
  7. Install the replacement throttle body.
  8. Torque fasteners to specification.
  9. Reconnect wiring.
  10. Perform throttle adaptation.
  11. Clear codes.
  12. Verify operation.

Replacing the Accelerator Pedal Assembly

Typical replacement steps include:

  1. Disconnect battery power.
  2. Disconnect the pedal connector.
  3. Remove mounting hardware.
  4. Install the replacement assembly.
  5. Tighten fasteners.
  6. Reconnect wiring.
  7. Perform calibration if required.
  8. Verify APP Sensor A and B operation.

Wiring Repairs

Repair damaged wiring by:

Avoid temporary repairs using household connectors or electrical tape alone.

Connector Repairs

Replace connectors that exhibit:

OEM-quality connector pigtails are recommended whenever available.

Throttle Relearn Procedures

Many vehicles require throttle adaptation after:

Relearn methods may include:

Always follow manufacturer procedures.

Verifying the Repair

After completing repairs:

  1. Clear all DTCs.
  2. Perform throttle relearn.
  3. Start the engine.
  4. Monitor live data.
  5. Compare Sensor A and Sensor B.
  6. Verify smooth throttle operation.
  7. Road test the vehicle.
  8. Recheck pending codes.
  9. Confirm Reduced Engine Power mode does not return.
  10. Confirm normal transmission operation and cruise control.

Because P0124 is intermittent, an extended road test is recommended before considering the repair complete.

Typical Repair Costs

RepairTypical Cost
Diagnostic testing$100–250
Wiring repair$150–500
Connector replacement$150–400
TPS replacement$100–350
Accelerator pedal assembly$150–600
Electronic throttle body$300–1,200+
PCM software update$100–300
PCM replacement$1,000–3,000+

Actual costs vary depending on the vehicle manufacturer and local labor rates.

Common Diagnostic Mistakes

Avoid these common mistakes:

Intermittent electrical faults reward patience—not parts cannon diagnostics.

Manufacturer-Specific Notes

General Motors

Inspect:

Ford

Monitor:

Harness movement near the throttle body is a known concern on some models.

Toyota and Lexus

Verify:

Connector corrosion should be ruled out before replacing the throttle body.

Honda and Acura

Inspect:

OEM replacement components are recommended.

Nissan and Infiniti

After repairs, perform:

Skipping these procedures may result in recurring drivability issues.

Hyundai and Kia

Inspect:

Volkswagen and Audi

Throttle adaptation is commonly required after:

BMW and MINI

Use manufacturer-level diagnostics to evaluate:

Chrysler, Dodge, Jeep, and Ram

Inspect:

Frequently Asked Questions

What usually fixes P0124?

The most common repairs include replacing a failing throttle-position sensor, repairing damaged wiring, replacing loose connectors, replacing an accelerator pedal assembly, or repairing intermittent ground circuits.

Can I drive with P0124?

Driving is not recommended because intermittent throttle faults can suddenly trigger Reduced Engine Power mode or poor throttle response.

Does P0124 always mean the throttle body is bad?

No. Wiring, connectors, pedal sensors, and ground faults are more common than complete throttle-body failure.

Can a loose connector cause P0124?

Yes. Loose connector terminals are one of the most common causes of intermittent throttle-position faults.

Can heat cause P0124?

Yes. Heat can expand damaged wiring, increase resistance, or expose failing electronic components.

Why does P0124 only happen over bumps?

Vehicle vibration often causes damaged wires or loose terminals to momentarily lose contact.

Final Thoughts

The P0124 Throttle/Pedal Position Sensor “A” Circuit Intermittent code indicates that the PCM has detected an unstable or unreliable signal from the primary throttle or accelerator-pedal position sensor.

Unlike permanent high- or low-voltage faults, intermittent failures often occur only under specific driving conditions, making careful diagnosis essential.

Successful repairs depend on confirming:

Avoid replacing expensive components until the intermittent fault has been positively identified.

A methodical diagnosis saves time, money, and frustration—and prevents the Check Engine Light from becoming your most persistent passenger.

Continue Your Pro Street DTC Series

Related guides include:

These articles provide additional troubleshooting information for related electronic throttle-control and accelerator-pedal system faults.

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