P2135
Throttle/Pedal Position Sensor/Switch A/B Voltage Correlation
Throttle / pedal position
Generic OBD-II
Medium
What it means
P2135 means the two internal throttle position sensor signals ('A' and 'B') no longer agree with each other. The ECM uses this redundancy as a safety check, so when the voltages disagree it usually forces the engine into reduced-power or limp mode. It most often points to a failing throttle body sensor or a wiring/connector fault.
Medium
Can I keep driving? Often limited — a correlation fault usually forces reduced-power/limp mode; drivable at low speed but full throttle response may be unavailable until repaired.
Common symptoms
What you'll notice
- Check-engine light on
- Reduced engine power / limp mode
- Surging or unstable idle
- Hesitation or poor throttle response
- Occasionally stalling or a hard start
Common causes
Most likely first
- Faulty throttle position sensor / throttle body (the two internal signals disagree)Likely
- Open, shorted, or chafed sensor harness wiringCommon
- Poor or corroded connection at the throttle body connectorCommon
- Faulty ECM/PCMLess often
How to diagnose & fix
Work through it in order
- Read freeze-frame and note the two TPS voltages to see which signal is off.
- Inspect the throttle body connector and harness for corrosion, bent pins, or chafing.
- With key on, confirm both sensor signals sweep smoothly and track each other as the throttle moves.
- Check the 5-volt reference and ground shared by both sensors.
- If the wiring is good but the signals still disagree, replace the throttle body / TPS and relearn idle, then retest.
FAQ
Quick answers
Is it safe to drive with P2135?+
Only cautiously. The car usually drops into reduced-power mode and can stall, so it is best to repair it promptly rather than drive far.
Can I just clear P2135?+
It returns quickly — the ECM constantly compares the two throttle-sensor signals, so it re-sets until the sensor or wiring is fixed.
Related codes
Often seen with P2135
Read & clear P2135 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX