P2135: The two throttle position sensors do not agree with each other
Throttle/Pedal Position Sensor/Switch A/B Voltage Correlation
Do not drive normally. The engine computer will enter a reduced-power or limp mode to protect safety. Drive directly to a shop, avoiding highways if possible.
What it means
Drive-by-wire throttle bodies have two independent position sensors built in that must agree within a calibrated range. If one reads 50 percent open and the other reads 20 percent open, the computer cannot trust either reading and sets P2135. It then limits throttle response as a safety measure. This is a safety-critical code because the computer cannot tell whether you are pressing the gas pedal or whether a sensor is lying. The throttle body itself is the most common repair, but test the wiring and connectors first because those cost nothing to inspect.
Common causes
- Failed throttle body with worn position sensorsThe most common fix. The dual sensor tracks inside the throttle body wear unevenly.
- Corroded or damaged throttle body connectorFive-wire connectors at the throttle body corrode and cause intermittent signal discrepancy.
- Damaged wiring in the throttle body harnessChafed wires cause one sensor signal to drop, creating an instant correlation fault.
- Carbon buildup preventing throttle plate movementIf the plate cannot move freely, both sensors may read correctly but report disagreement at partial travel.
What it costs
- Throttle body cleaning$80 to $150
- Throttle body connector repair$60 to $200
- Throttle body replacement$200 to $600
Symptoms
- Reduced engine power or limp mode
- Poor acceleration or throttle response
- Vehicle will not accelerate above a low speed
- Hesitation or surging
- Check engine light on
What to do next
Check the throttle body connector first. Unplug it and look for bent pins, green corrosion, or moisture. Clean and reseat it. If the code persists, clean the throttle body. If neither helps, the throttle body assembly needs replacement. After any throttle body work, perform the electronic throttle control reset procedure for your vehicle or the idle may not calibrate correctly.
Lewis shows both throttle position sensor voltages in real time so you can see the exact gap between the two readings and confirm whether they diverge at a specific throttle angle. Download Lewis.
Related codes
FAQ
- Can I drive in limp mode to the shop?
- Yes, slowly and on surface streets. Limp mode limits power to keep you safe. Avoid highway speeds.
- Will cleaning the throttle body fix this?
- Occasionally, if carbon is restricting plate movement. But if the sensor tracks inside are worn, cleaning will not fix the internal sensor disagreement.
- Does the throttle body need to be programmed after replacement?
- On most drive-by-wire vehicles, yes. An idle relearn or throttle body calibration procedure is required. Your shop will handle this, but confirm they are doing it.