P0124 – Throttle Position Sensor/Switch A Circuit Intermittent

The P0124 engine code indicates an intermittent problem with the Throttle/Pedal Position Sensor/Switch "A" Circuit. If your vehicle is displaying this code, it's important to diagnose and fix the issue promptly. While it may be possible to continue driving for a short time, it's best to have the problem checked by a mechanic as soon as possible to prevent further damage and ensure safe operation.

About the P0124 Code

The P0124 code is a generic powertrain code that applies to many makes and models. It signals that the voltage from the "A" circuit of the Throttle Position Sensor (TPS) or Accelerator Pedal Position Sensor (APPS) is intermittently falling outside the expected range.

The key components involved are:

• Throttle Position Sensor (TPS): Mounted on the throttle body, the TPS measures the throttle valve angle and sends a voltage signal to the Engine Control Module (ECM).
• Accelerator Pedal Position Sensor (APPS): Detects the position of the accelerator pedal and transmits this information to the ECM to control the throttle.
• Wiring and Connectors: Carries the voltage signals between the sensors and ECM.

These sensors are critical for proper throttle control, engine performance, fuel efficiency, and emissions.

Common Causes

Some of the most frequent causes of the P0124 code include:

• Faulty TPS or APPS due to wear, contamination, or improper adjustment
• Damaged, loose, or corroded wiring and connectors in the sensor circuits
• Issues with the throttle body such as carbon buildup or binding
• Outdated software in the Powertrain Control Module (PCM)

Diagnosis

To properly diagnose the root cause of P0124, follow these steps:

1. Connect a scan tool and check for any other codes. Make note of freeze frame data.
2. Perform a thorough visual inspection of the wiring and connectors for the TPS and APPS. Look for damage, loose connections, or corrosion.
3. Using a digital multimeter, test the voltages at the TPS and APPS. Compare the readings to specifications, which are typically 0.5-0.7 V at closed throttle and 3.5-4.5 V at wide open throttle.
4. Check for any applicable Technical Service Bulletins (TSBs) that may address known issues with the TPS, APPS, or PCM software.

Repair Solutions

Depending on the diagnosed cause, the fix for P0124 may involve:

• Replacing the TPS or APPS if testing reveals them to be faulty. Expect to pay around $120-$300 USD ($100-€250 EUR) for parts and labor.
• Repairing damaged wiring or connectors and ensuring proper routing and connections.
• Cleaning the throttle body and checking for proper operation.
• Updating the PCM software if an applicable TSB calls for it.

Prevention

To help prevent P0124 and related issues:

• Stick to the manufacturer's recommended maintenance schedule, including regular throttle body cleaning.
• Keep the engine control system up-to-date with the latest software.
• Address any potential sources of contamination, such as oil leaks or excess moisture.

Related Issues

Other codes that may appear along with P0124 include:

• P0120-P0123, P0220-P0229: Other faults related to the TPS or APPS
• P0300-P0305: Misfires that may be caused by inaccurate throttle control
• P0171-P0175: Fuel trim issues that can result from improper TPS/APPS operation

These codes can help pinpoint the underlying problem and guide the diagnostic process. By promptly addressing P0124 and any related faults, you can restore proper throttle control and prevent potentially serious drivability and emissions issues down the road.

Frequently Asked Questions About P0124 Engine Code

What does the P0124 code mean?

The P0124 code indicates an intermittent problem with the Throttle/Pedal Position Sensor/Switch “A” Circuit. This means the voltage from the throttle position sensor (TPS) or accelerator pedal position sensor (APPS) is intermittently falling outside the expected range.

What are the common symptoms of code P0124?

Common symptoms include intermittent hesitation or stumbling on acceleration, fluctuating engine performance, occasional difficulty maintaining speed, reduced fuel efficiency, and in some cases, the Check Engine Light may be on.

Is it safe to drive with a P0124 code?

While you may be able to drive short distances with a P0124 code, it’s best to diagnose and fix the issue promptly to avoid further damage and ensure safe, reliable operation. The intermittent nature of the problem could lead to unexpected power loss while driving.

What causes the P0124 code to set?

Potential causes include a faulty TPS or APPS, damaged or corroded wiring and connectors in the sensor circuit, issues with the throttle body such as carbon buildup or binding, or in rare cases, a problem with the powertrain control module (PCM) software.

How do you diagnose the cause of code P0124?

Diagnosis typically starts with a visual inspection of the wiring and connectors, followed by testing the TPS and APPS voltages with a multimeter. Comparing the readings to specifications can reveal a faulty sensor. Monitoring live data with a scan tool while wiggle-testing the wiring can help pinpoint intermittent issues.

Can a bad throttle position sensor cause a P0124 code?

Yes, a failing throttle position sensor is one of the most common causes of the P0124 code. The TPS may be worn out, improperly adjusted, or have an intermittent open or short circuit causing the voltage signal to fall out of range.

How much does it cost to fix code P0124?

The cost to repair a P0124 code can range from under $100 for a simple wiring repair or sensor adjustment to $200-$600 to replace the throttle position sensor or accelerator pedal position sensor. In rare cases involving PCM issues, costs could be higher.

Can I replace the throttle position sensor myself?

Replacing the TPS is usually straightforward on most vehicles and can be done by a competent DIYer. It typically involves disconnecting the battery, unplugging the sensor, removing the mounting screws, installing the new sensor, and reconnecting the wiring. An adjustment procedure may be needed after replacement.

What happens if I don’t fix a P0124 code?

Ignoring a P0124 code can result in worsening drivability problems, poor fuel economy, and possible damage to other components like the catalytic converter due to improper fuel mixtures. In some cases, the intermittent issue could cause a sudden loss of power which may be dangerous while driving.

Can a weak battery cause a P0124 code?

While a weak battery alone is unlikely to directly cause a P0124 code, low system voltage could lead to intermittent sensor readings if it drops below the normal operating range. Always ensure the battery is fully charged and in good condition during diagnosis.

Can a vacuum leak cause code P0124?

A vacuum leak near the throttle body could potentially allow unmetered air to enter the engine, causing the PCM to detect a discrepancy between expected and actual airflow. While more likely to set a lean code like P0171, this could contribute to intermittent TPS readings in some cases.

What does an intermittent P0124 code mean?

An intermittent P0124 code means the fault condition is not consistently present. The problem may come and go, making it harder to diagnose. Intermittent issues are often caused by faulty wiring connections, loose solder joints on circuit boards, or a failing component that works sporadically.

Can a dirty throttle body cause a P0124 code?

Yes, a throttle body that is heavily contaminated with carbon buildup can cause binding or sticking, which may lead to intermittent TPS readings as the throttle plate does not smoothly follow the accelerator input. Cleaning the throttle body may resolve the issue in this case.

How do you test a throttle position sensor?

To test a TPS, first check for any stored codes and record freeze frame data. Next, visually inspect the wiring and connector for damage. With the key on, engine off, use a multimeter to check the reference voltage (usually 5V) and ground signals at the sensor. Then monitor the voltage change as you slowly move the throttle from closed to wide open. The voltage should increase smoothly, typically from around 0.5V to 4.5V.

What is the location of the throttle position sensor?

The TPS is typically mounted on the throttle body, which is attached to the intake manifold. It usually has a 3-wire or 4-wire connector and an arm or lever that rotates with the throttle shaft to track its position. Refer to a vehicle-specific repair manual or database for the exact location on your make and model.

How do you perform a throttle position sensor adjustment?

TPS adjustment procedures vary by vehicle. Some have an adjustable mounting base that allows the sensor to be rotated slightly to set the idle voltage. Others are not adjustable and must be replaced if out of specification. Consult the factory service information for the proper procedure for your vehicle.

Can a faulty accelerator pedal position sensor cause code P0124?

Yes, on drive-by-wire systems that use an accelerator pedal position sensor (APPS) instead of a cable-actuated throttle, a failing APPS can cause similar symptoms to a faulty TPS and may trigger a P0124 if the voltage readings intermittently fall out of range.

What other codes may be present with P0124?

Related codes that may occur along with P0124 include other throttle position sensor codes like P0121, P0122, and P0123, as well as accelerator pedal position sensor codes P2120-P2122. Misfire codes P0300-P0308 or lean codes P0171-P0175 may also be present due to the intermittent airflow issues.

Can a P0124 code clear itself?

Yes, if the intermittent fault condition that caused the code is no longer present, the PCM may automatically clear the code after a certain number of drive cycles with no recurrence of the problem. However, it’s still important to diagnose the underlying cause to prevent the issue from returning.

How do I clear a P0124 code?

After diagnosing and repairing the cause of the P0124 code, the code can be cleared using an OBD-II scan tool. Most scan tools have an option to clear codes or reset the PCM. Disconnecting the battery for a few minutes will also clear the code, but this method will reset all learned values and may cause other temporary issues. It’s best to use a scan tool for code clearing.