P2138 on Chevrolet Impala
Throttle/Pedal Position Sensor/Switch D/E Voltage Correlation
Methodology: Reviewed against the SAE J2012 generic DTC definition and NHTSA owner-complaint patterns, then scoped to Chevrolet Impala context without treating complaints as confirmed diagnoses.
Sources: SAE/OBD-II definitions, manufacturer service information, and public reliability reports (including NHTSA where applicable).
- SAE J2012 Diagnostic Trouble Code Definitions — Generic diagnostic trouble code definition reference for P2138.
- NHTSA recalls, complaints, and manufacturer communications — Used to check public owner complaint context, recall status, and safety-related manufacturer communications by VIN or vehicle.
Limits: Guidance is informational and may not match every model-year or revision. Confirm with the official manual and diagnostics before replacing parts. For safety-critical or electrical work, use a qualified technician.
What P2138 Means on Your Chevrolet Impala
P2138 is a diagnostic trouble code indicating: Throttle/Pedal Position Sensor/Switch D/E Voltage Correlation. This code relates to the powertrain system. The vehicle's computer detected a condition outside normal operating parameters and stored this code.
Real Chevrolet Impala Owner Reports
Source: NHTSA Complaints Database
"I got a P2138 code for Accelerator Pedal Sensor error. From what I have seen this is caused by the two sensors not matching. I have repaired this issue previously about 3 years ago, but it has happened again. This seems to be a common issue with GM cars of this era."
"Displayed on panel "reduced engine power" . on star diagnosed service code "p2138". on 05/01/2012 while driving through a large intersection my engine power was reduced to 3 or maybe 5 mph. i was trying to get through the intersection without the acceleration that was so desperately needed."
""reduced engine power" service code p2138. on 05/01/2012 while driving through an intersection my engine power was reduced to 3, maybe 5 mph. i was trying to get through that intersection without the acceleration that was so desperately needed. this is definitely a safety issue."
"Check engine light Code p2138 Change the throttle pedal position sensor the next day the car dropped down to 5 to 10 mph information center said engine safety been reduced to 5 to 10 mph plus my traction control light came on then information center said service traction control put my old thrott"
"The gas petal sensor is reading a code P2138 (Accelerator Petal Position Sensors 1-2 not plausible). My father has changed the petal not once but twice and erased the code but it keeps coming back. Also getting a p0172 code as well."
All reports filed by vehicle owners directly with the U.S. Department of Transportation.
📊 Complaint Trend by Model Year
Common Causes on Chevrolet Impala
Based on NHTSA complaint component analysis for this vehicle.
What To Do Next
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1
Check for recalls on YOUR VIN
Go to nhtsa.gov/recalls and enter your VIN. If your vehicle is covered, repairs are free.
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2
Get a proper diagnosis
A code alone doesn't tell you the exact failed part. A diagnostic at a shop ($50–$150) pinpoints the root cause before you spend money on parts.
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3
Compare repair quotes
Get 2–3 quotes. Dealer vs. independent shop prices often differ 30–50% for the same repair.