OBD-II Generic Error Code P2138: How to Fix It

Q: Can I drive my car with a P2138 code?

Driving with P2138 is not recommended for extended periods. The code often triggers reduced engine power mode, which limits throttle response and can make the vehicle feel sluggish or unresponsive — particularly dangerous in situations requiring quick acceleration such as merging onto a highway. For short, low-speed trips to a repair shop it may be possible, but you should address this fault as soon as possible.

Q: What is the most common cause of code P2138?

The most common cause of P2138 is a failing accelerator pedal position (APP) sensor assembly. Over time the dual internal sensors within the assembly can wear and produce signals that no longer match the expected correlation. Corroded or damaged wiring connectors at the APP sensor are a close second cause and should always be inspected first since they are a free fix.

Q: How much does it cost to fix a P2138 code?

If the fix is a simple connector cleaning or minor wiring repair, cost can be minimal — just your time. Replacing an accelerator pedal position sensor assembly typically costs between $50 and $200 for the part, plus $75 to $150 in labor if done at a shop. Replacing an electronic throttle body is more expensive, generally $150 to $400 for the part plus $100 to $200 in labor. ECM replacement, if ever needed, can exceed $500 to $1,500 depending on the vehicle.

Q: Will P2138 clear itself after the problem is fixed?

Once the underlying fault is repaired, the code will typically clear itself after a set number of successful drive cycles — usually 3 to 5 cycles without the fault reoccurring. However, it is best practice to manually clear the code with an OBD2 scanner after the repair so you can immediately confirm whether the fix was successful on your next test drive rather than waiting for the self-clear.

Q: Is P2138 the same as P0120 or other throttle codes?

Not exactly. P0120 relates to a general throttle/pedal position sensor circuit malfunction for sensor A, while P2138 specifically flags a voltage correlation failure between sensors D and E — meaning the two sensors are not tracking together as expected. Both codes involve the throttle or pedal position sensing system, but P2138 is specifically a rationality or correlation fault rather than a simple out-of-range voltage fault. It is common for multiple throttle-related codes to appear together, so always address all stored codes.

Abstract

OBD-II code P2138 indicates that the voltage signals from two of the throttle position or accelerator pedal position sensors (sensors D and E) are not correlating as expected by the engine control module (ECM). This mismatch prevents the ECM from accurately reading how far you are pressing the accelerator, which can trigger reduced engine power mode, hesitation, or stalling. The fault is most commonly caused by a failing throttle body, a damaged accelerator pedal position (APP) sensor, or wiring issues between those components and the ECM.