Throttle/Pedal Position Sensor/Switch D/E Voltage Correlation
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.
- Keep driving?
- No -- stop driving
- DIY difficulty
- moderate
- Estimated cost
- $100 - $400 (parts and labor)
Best-selling code reader on Amazon. Reads and clears check engine codes on any 1996+ vehicle. Under $30.
Check Price on AmazonAffiliate link -- we earn a commission at no extra cost to you.
Essential for diagnosing sensor codes, checking voltage, and testing circuits. Under $15 and pays for itself on the first job.
Check Price on AmazonAffiliate link -- we earn a commission at no extra cost to you.
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
-
Compare APP sensor D and E voltages on scan tool -- they should maintain a fixed ratio at all pedal positions
-
Slowly press pedal while graphing both D and E signals -- look for divergence or crossing
-
Inspect APP sensor connector under the dash for corrosion or moisture
-
Check wiring from APP sensor to PCM for both D and E circuits -- verify continuity and no shorts
-
Replace accelerator pedal assembly if D/E correlation is off with good wiring
Common Fixes by Vehicle
What techs usually find when diagnosing P2138 on specific vehicles — tap your vehicle for the fix and the exact part:
2002-2015 Toyota Camry/Corolla/RAV4/Highlander easy DIY
Replace accelerator pedal position sensor (integrated with pedal assembly). Toyota APPS fails from internal wear; don't clean, just replace. Use Denso OEM pedal. Secondary cause: ECU connector water damage on flood-damaged vehicles.
Labor: 30 min2005-2015 GM Equinox/Malibu/Cobalt/HHR easy DIY
Replace accelerator pedal assembly -- GM drive-by-wire pedal TPS fails over time. AC Delco OEM required; off-brand pedals often throw P2138 within weeks. Also check for ECU update (GM has TSB for pedal logic).
Labor: 30 min2004-2014 Nissan Altima/Maxima/Sentra easy DIY
Check accelerator pedal ground (chassis ground near firewall). Nissan grounds corrode -- clean and re-torque first. If code persists, replace pedal assembly (OEM Hitachi). Perform throttle relearn after replacement.
Labor: 45 minFrequently 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.
Sources
This page is built from documented references. Verify against your own service info before repair work.
P2138 on Diesel, EV & Equipment
The same code ID appears across other engines and platforms. The diagnostic flow varies by manufacturer — these are the platform-specific breakdowns:
See All Codes & Fixes for Your Vehicle
Explore More
Was this helpful?
Share carcodefinder.com with a friend who needs to decode their check engine light.