Throttle/Pedal Position Sensor/Switch A/B Voltage Correlation
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.
- Keep driving?
- No — stop driving
- DIY difficulty
- hard
- Estimated cost
- $0 for throttle body cleaning; $150-$400 for throttle body replacement
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What Are the Symptoms of P2135?
- Reduced Engine Power light on
- Limp mode
- Unresponsive throttle
- Possible stalling
What Causes P2135? (Most Likely First)
- 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
Can I Still Drive with P2135?
No — stop driving. P2135 is rated critical severity. Continuing to drive in this state risks further damage — get it looked at before your next trip.
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.
Mechanics Guide Step-by-step diagnosis
How Do You Diagnose P2135?
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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.
Sources 1
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
P2135 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:
Which Vehicles Commonly Get P2135?
- Chevrolet Cobalt, Malibu, HHR (2.2L, 2.4L Ecotec)
- Pontiac G6 and Solstice
- Saturn Ion
- Chevrolet Silverado and Tahoe (V8)
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