What Does P2138 Mean?
The PCM detects improper voltage correlation between throttle/pedal position sensors D and E. These redundant sensor signals should maintain a specific relationship; deviation indicates sensor failure, electrical fault, or signal circuit damage.
Safety Warning
Vehicle will enter limp mode immediately with severe power restriction. Not safe for normal driving conditions; proceed slowly to repair shop only.
Common Causes
50%
Failed accelerator pedal position (APP) sensor assembly
25%
Damaged or corroded APP sensor connector or wiring
15%
Failed throttle body position sensor (if D/E sensors are TPS-based)
7%
PCM 5V reference voltage circuit fault
3%
Ground circuit issue at sensor or PCM
Diagnostic Steps
1
Step 1: Monitor APP sensors D and E voltages with scan tool during pedal movement; verify they track in opposite directions with proper voltage ranges
2
Step 2: Disconnect APP sensor connector and inspect terminals for corrosion, pushed-back pins, or damage; clean and repair as needed
3
Step 3: Measure reference voltage (5V) and ground at APP sensor connector with key on, engine off
4
Step 4: Check signal wire resistance from sensor connector to PCM; should be less than 1 ohm with no shorts to ground or voltage
5
Step 5: Replace APP sensor if all circuits test normal but correlation fault persists
Estimated Repair Cost
$150 - $600
Parts + labor, varies by vehicle and location
The PCM detects improper voltage correlation between throttle/pedal position sensors D and E. These redundant sensor signals should maintain a specific relationship; deviation indicates sensor failure, electrical fault, or signal circuit damage.
The most common cause of P2138 (Throttle/Pedal Position Sensor/Switch D/E Voltage Correlation.) is: Failed accelerator pedal position (APP) sensor assembly
Typical repair costs for P2138 range from $150 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle will enter limp mode immediately with severe power restriction. Not safe for normal driving conditions; proceed slowly to repair shop only.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P2138 to identify the root cause.
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Quick Info
Category
Powertrain
System
Electronic Throttle Control
Difficulty
Type
Generic (SAE)
Recommended Tools
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