Throttle/Pedal Position Sensor/Switch D/E Voltage Correlation
What does P2138 mean?
The P2138 code means the vehicle's onboard diagnostic system has detected: Throttle/Pedal Position Sensor/Switch D/E Voltage Correlation. This is a critical severity code.
Common Symptoms
- Severe reduced power or no acceleration
- Accelerator pedal unresponsive
- Engine idles only
- Multiple throttle system warnings
- Check engine light on
Probable Causes (Ranked by Likelihood)
- Faulty accelerator pedal position sensor (D/E tracks disagree) Very High
- Corroded APP sensor connector High
- Wiring damage causing one track to read incorrectly Moderate
- Water intrusion in APP sensor connector Moderate
- PCM input circuit issue affecting one track Low
Step-by-Step Diagnostic Procedure
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Compare APP sensor D and E voltages on scan tool -- they should maintain a fixed ratio at all pedal positions
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Slowly press pedal while graphing both D and E signals -- look for divergence or crossing
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Inspect APP sensor connector under the dash for corrosion or moisture
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Check wiring from APP sensor to PCM for both D and E circuits -- verify continuity and no shorts
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Replace accelerator pedal assembly if D/E correlation is off with good wiring
Frequently Asked Questions
Can I drive with code P2138?
No. When the D and E tracks of the APP sensor disagree, the PCM cannot determine actual pedal position and shuts down throttle control. The vehicle will only idle and the pedal may be completely unresponsive.
What causes D/E correlation to fail?
The most common cause is a failing APP sensor where one track has worn out or drifted while the other still reads correctly. Connector corrosion that affects one pin more than another can also cause the two signals to diverge.
Is the pedal assembly hard to replace?
No. The accelerator pedal assembly is typically held in with 2-3 bolts and one electrical connector. The job takes 20-40 minutes for most vehicles. The pedal assembly typically costs $80-$250 depending on the vehicle. No special tools are needed.