Throttle/Pedal Position Sensor/Switch A / B Voltage Correlation
Your car's throttle and accelerator pedal sensors are sending conflicting signals to the engine computer, like two GPS devices disagreeing on your location. The ECU detects a mismatch between what the pedal position should be and what the throttle body position actually is.
The ECU monitors two independent throttle/pedal position sensors (TPS A and TPS B) that should track together proportionally. When the voltage correlation between these sensors drifts beyond acceptable limits, the ECU triggers a fault code to prevent drivability issues and potential runaway throttle conditions.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| TPS A/B Voltage Correlation | Sensors track within 10% voltage variance | Voltage difference exceeds 10% or sensors disagree on position |
| Sensor Response Time | Both sensors respond simultaneously to pedal input | Response time variance indicates sensor lag or failure |
Code P2135 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P2135 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.