Chevy Check Engine Code
P2138 on Chevy
Throttle / Pedal Position Sensor D / E Voltage Correlation
Also covers: Chevrolet, GMC, Buick, Cadillac, GM
P2138 on Chevy: what makes it different
P2138 on GM vehicles indicates the throttle/accelerator pedal position sensors disagree (Sensor D vs Sensor E voltage correlation fault). On Chevy trucks and SUVs this throws limp mode — and it's almost always the pedal-position sensor in the accelerator pedal assembly, not the throttle body.
Most-affected engines
- Most GM vehicles 2005+ with electronic throttle (Silverado, Tahoe, Suburban, Sierra, Equinox, Traverse, Impala, Malibu)
Common model years: 2005–present
Most likely cause on Chevy
Failed accelerator pedal position sensor (APP)
Known Chevy engine-family issues
On 2007–2014 GM trucks (Silverado, Tahoe, Suburban, Sierra, Yukon), the accelerator pedal assembly is one of the top-3 most-replaced electronic parts. The pedal position sensor is mechanically loaded every press; the dual-track potentiometer wears out and the two outputs drift apart. Once they disagree by more than the PCM's threshold, P2138 sets and the truck goes to limp mode (idle or near-idle only).
Chevy-specific causes (most common first)
- Failed accelerator pedal position sensor — the dual-sensor inside the gas pedal disagrees about pedal angle. Replace the entire pedal assembly (GM part numbers vary; aftermarket Standard Motor Products APS-149 etc., $90–$200)
- Corroded/loose APP connector (very common on Silverados that see road salt — water wicks down the harness into the pedal connector)
- Damaged APP wiring at the firewall pass-through
- Throttle body (TAC) fault — much less common than pedal sensor on GM
- PCM software needing pedal relearn after battery disconnect (does not throw P2138 on its own but can mask the real cause)
Chevy-specific diagnostic tip
P2138 with limp mode that comes and goes (worst in cold/wet weather) is usually a corroded APP connector — unplug the pedal connector, inspect for green/white corrosion on the pins, clean with electrical contact cleaner, repack with dielectric grease. Sometimes restores function for years; sometimes buys you a week before you need the new pedal.
Symptoms drivers report
- Check engine light
- Reduced engine power / limp mode
- No throttle response
- Stalling
Typical repair cost on Chevy
Most Chevy owners fix P2138 for between $100 and $350, depending on which underlying cause turns out to be at fault. Start with the most-likely cause for your vehicle — Failed accelerator pedal position sensor (APP) — before throwing parts at it.
Chevy P2138 FAQ
My Silverado is stuck at idle with P2138 — can I drive it home?
In most cases yes — P2138 puts the truck in "fail-safe idle" mode where the engine runs at idle RPM and doesn't respond to the pedal. You can usually creep along at idle (~10 mph) on flat ground but expect zero power. Cycle the key off and back on at a safe stop — sometimes the PCM re-checks the sensors and restores partial pedal control until the next failure event.
Related codes
Drive a different make? See the general P2138 guide for cross-vehicle causes and symptoms.
Confirm P2138 on your Chevy in 60 seconds
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