P2135 Throttle/Pedal Position Sensor/Switch A/B Voltage Correlation

P2135 means the two throttle-position (or pedal) sensor signals that should track together no longer agree. Drive-by-wire systems use dual sensors as a safety check, and a mismatch triggers this fault.

Code details

Generic OBD-II · P2

System: Speed / Idle
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not replace the throttle body before checking the connector and wiring, because a corroded pin or bad ground is a frequent cause of correlation faults.

Symptoms of P2135

Reduced-power / limp mode, often the main symptom.
Poor or dead throttle response.
A warning light on the dash.

Common causes of P2135

A failing throttle-position sensor pair.
Corroded or spread connector pins.
Wiring, reference, or ground faults.
A contaminated throttle body affecting the signal.

Useful checks before replacing parts

Compare the two sensor voltages live through a sweep.
Inspect the sensor connector and wiring for corrosion or spread pins.
Check for a shared reference or ground fault affecting both signals.

Related OBD-II codes

These nearby speed / idle entries can help compare wording and pin down the fault area.