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P2138
System
Powertrain (Throttle)
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Enhanced OBD2 scanner (live data graphs, freeze frame, battery voltage test)

Throttle/Pedal Position Sensor D/E Voltage Correlation

Understand P2138, common causes, and the right TOPDON scanner to diagnose it.

Two pedal position sensors disagree — safety cutback on throttle opening.

Common symptoms

  • Engine power reduced
  • Limp home mode

Typical causes

  • Pedal sensor failure
  • Misaligned pedal assembly
  • Wiring fault

What scanner do you need?

Enhanced OBD2 scanner (live data graphs, freeze frame, battery voltage test)

Use live data and freeze frame to confirm the fault before replacing parts. ABS, SRS, and network U-codes usually require a full-system scanner.

Diagnostic tips

  • Record freeze frame data when the code first sets
  • Clear the code only after fixing the root cause
  • Check for related pending codes that point to a common issue
  • Verify battery voltage is above 12.4V before chasing sensor codes

Recommended TOPDON scanners

Frequently asked questions

What does P2138 mean?
P2138 indicates throttle/pedal position sensor d/e voltage correlation. Two pedal position sensors disagree — safety cutback on throttle opening.
Can I diagnose P2138 with a basic code reader?
P2138 may set in the engine module, but related diagnostics often benefit from an enhanced or full-system scanner with live data and freeze frame.
Which TOPDON scanner do I need for P2138?
Enhanced OBD2 scanner (live data graphs, freeze frame, battery voltage test) See recommended tools on this page.
Is it safe to drive with P2138?
It depends on the code and symptoms. Flashing check engine lights and misfire codes should be addressed immediately. Consult a professional if unsure.