Is the pedal the only thing I need to replace?

If only P2138 is set and no P2135, then the pedal assembly is the most likely fix. If P2135 is also set, inspect the shared wiring harness.

Does the new pedal need programming?

On most vehicles, no. The PCM reads the raw voltage and compares the two signals. Plug in the new assembly and it works.

How do I access the pedal connector?

It is under the dash near the firewall. You may need to remove a kick panel or reach underneath. A flashlight will show it clearly.

Codes › P2138

P2138: The two accelerator pedal position sensors do not agree

Throttle/Pedal Position Sensor/Switch D/E Voltage Correlation

High severityCan you keep driving?

Do not drive normally. Limp mode will restrict power. Drive carefully to a shop, avoiding highways.

What it means

Like the throttle body, the accelerator pedal on a drive-by-wire system has two position sensors that must agree. P2138 means they do not. The car cannot tell reliably how far you are pressing the pedal, so it limits throttle as a safety measure. P2138 is the pedal version of P2135; if both codes appear, suspect the wiring harness or connector that feeds both pedal and throttle sensors. If only P2138 appears, the issue is at the pedal itself. Accelerator pedal assemblies are relatively affordable to replace and do not require programming on most vehicles.

Common causes

Failed accelerator pedal position sensor assemblyThe dual sensors in the pedal assembly wear out. The whole pedal assembly is replaced as a unit.
Damaged or corroded connector at the pedalThe connector under the dash near the pedal can corrode from moisture.
Damaged wiring harness near the pedalWires can be pinched or chafed near pedal pivot points.

What it costs

Accelerator pedal connector cleaning$0 to $50
Accelerator pedal assembly replacement$80 to $250

Symptoms

Limp mode or reduced power mode
Poor or delayed throttle response
Vehicle will not accelerate normally
Check engine light on

What to do next

Locate the accelerator pedal connector under the dash, unplug it, and inspect for corrosion or damaged pins. Clean the contacts and reconnect. If the code returns, replace the pedal assembly. On most vehicles this is a straightforward DIY repair: three or four bolts and one connector. No programming is needed for the pedal on most platforms.

Lewis shows both accelerator pedal sensor voltages side by side, so you can confirm whether the discrepancy is at the pedal or in the shared wiring between pedal and throttle. Download Lewis.

Related codes

FAQ

Is the pedal the only thing I need to replace?: If only P2138 is set and no P2135, then the pedal assembly is the most likely fix. If P2135 is also set, inspect the shared wiring harness.
Does the new pedal need programming?: On most vehicles, no. The PCM reads the raw voltage and compares the two signals. Plug in the new assembly and it works.
How do I access the pedal connector?: It is under the dash near the firewall. You may need to remove a kick panel or reach underneath. A flashlight will show it clearly.