P2135 explained: A/B position-signal correlation, reduced power and throttle-sensor or wiring checks before replacing parts.
Meaning, symptoms, causes and checks
P2135 means position signals A and B do not meet the controller's expected relationship. In the referenced GM, Mazda and Acura applications, the code concerns throttle-position sensors. The generic wording is not a reason to replace the accelerator pedal automatically. Identify the exact circuit in the vehicle documentation; electrical thresholds and procedures vary by application.
Affected system: Powertrain
Symptoms
- Check-engine light and a possible reduced-power message.
- Throttle response may be limited or irregular; the code alone does not identify the cause.
Possible causes
- Disagreement between the two position-sensing channels, including an internal assembly problem.
- Contacts or wiring that disturb the signals; documented cases include application-specific electrical conditions.
- An unsuitable replacement or post-repair procedure, where history and an applicable bulletin support that condition.
What to check
- Save codes and associated data; note whether the concern followed throttle-body replacement.
- Identify what A/B means on the exact vehicle; do not equate P2135 automatically with a pedal fault.
- Inspect accessible connectors and wiring, then test supply, ground and signals against the manufacturer diagram.
- Compare both position channels with the specified relationship; do not assume identical signals or a universal threshold.
- Match bulletins to VIN and engine before replacing the assembly. The GM and Mazda cases specify different procedures.
- Do not force an electronic throttle or work on it with ignition on; perform relearning after repair only when specified.
Also written as: P2135-00, P213500 (some scan tools add the fault-type byte, e.g. -00).