P2135: The two throttle position sensors do not agree with each other
Throttle/Pedal Position Sensor/Switch A/B Voltage Correlation
The two throttle position signals disagree, so the car usually cuts power into limp mode. Get it checked today and stay off highways. If the throttle stops responding, pull over.
Stop driving and get help if
- The check engine light is flashing
- The temperature gauge runs high, or you see steam (overheating)
- The car loses power, hesitates badly or stalls
- You smell burning or see smoke
- A brake warning light comes on, or the brakes feel different
Pull over as soon as you can, turn the engine off, and call a tow or roadside help.
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 the fix could involve
From the cheaper fix to the bigger one. Prices depend on your car, your area and the shop, so ask for a written quote that names the part and the labor before you approve it.
- Throttle body cleaning
- Throttle body connector repair
- Throttle body replacement
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 the live throttle position reading alongside any related throttle and pedal codes, so you can see whether the reading behaves strangely at specific pedal positions. Get Lewis on the App Store or Google Play.
Related codes
FAQ
- Can I drive in limp mode to the shop?
- Limp mode cuts power because the computer cannot trust the throttle signal. Get it checked today and stay off highways. If the throttle stops responding or the car hesitates in traffic, pull over and have it towed.
- 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.
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