Throttle/Pedal Position Sensor/Switch A/B Voltage Correlation
What does P2135 mean?
The P2135 code means the vehicle's onboard diagnostic system has detected: Throttle/Pedal Position Sensor/Switch A/B Voltage Correlation. This is a critical severity code.
Common Symptoms
- Reduced Engine Power light on
- Limp mode
- Unresponsive throttle
- Possible stalling
Probable Causes (Ranked by Likelihood)
- Failed throttle body with mismatched TPS signals High
- Carbon buildup causing TPS 1 and TPS 2 signals to diverge High
- Wiring fault causing signal corruption on one TPS circuit Moderate
- Failed accelerator pedal position sensor Moderate
Step-by-Step Diagnostic Procedure
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Monitor TPS 1 and TPS 2 simultaneously on a scan tool. They should move in opposite and proportional directions through the full throttle range.
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Clean the throttle body and test again. Carbon can cause inconsistent readings.
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If TPS 1 and TPS 2 diverge or one stays flat, the throttle body needs replacement.
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Also monitor accelerator pedal position sensor 1 and 2 for correlation issues.
Frequently Asked Questions
Why does P2135 put my car in limp mode?
Modern drive-by-wire systems use two independent throttle position sensors for redundancy and safety. If their signals do not correlate (agree), the ECU cannot trust either reading and enters reduced power mode as a safety precaution.