P2135: Throttle/Pedal Position Sensor A/B Voltage Correlation
Severity: high
What it means: The engine computer compares two position signals on the electronic throttle (or gas pedal), and they don't agree. Because it can't trust the throttle, it usually limits power.
Safe to drive? Drive only to get it fixed. The car often goes into reduced power (limp mode), which can make merging or passing dangerous.
Common symptoms
- Reduced engine power or limp mode
- Check engine or throttle warning
- Poor or no response to the gas pedal
- Stalling or rough idle
Likely causes, ranked
- Worn or failing electronic throttle bodyShop
- Wiring or connector problem at the throttle bodyDIY
- Gas pedal position sensor faultShop
Vehicle-specific notes
- 2001–2007 Volvo V70: On Volvo V70, S60 and XC70 models with the electronic throttle module, owners on Matthews Volvo Site and SwedeSpeed traced limp mode to the throttle module or its connections. Volvo recall 06V441 covered a throttle-related software update on some 2001–2002 cars. Read the full answer · Source
What it means: The engine computer compares two position signals on the electronic throttle (or gas pedal), and they don't agree. Because it can't trust the throttle, it usually limits power.
Severity: High. Safe to drive? Drive only to get it fixed. The car often goes into reduced power (limp mode), which can make merging or passing dangerous.
DIY or shop?
DIY for cleaning and checking the throttle body connector; shop for throttle body replacement and relearn.
Before you replace parts
- Read all stored codes and freeze-frame data.
- Check the throttle body connector and wiring for corrosion or loose pins.
- Check your VIN for recalls and service bulletins on the throttle.
- After any throttle work, do the throttle relearn the manufacturer calls for.
Safety / mechanic note
Verify with a mechanic. Limp mode can leave you without power in traffic. A code points to a circuit or system, not always a specific part.