What it means
The A and C throttle or pedal position signals do not agree within the allowed range. The code identifies a correlation fault; the affected sensors and any resulting fallback strategy depend on the vehicle.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
- The engine or gearbox may go into limp mode
How it works
Position channels A and C provide related feedback from the throttle or pedal system, depending on the vehicle's design. P2136 sets when the control module detects that those two signals no longer agree within their expected relationship, which can indicate a worn track or leakage or poor contact at a connector.
Common causes
Most likely first.
- One sensor track worn
- Connector corroded with leakage
Symptoms
- Check engine light on
- Reduced throttle response, possible limp mode
- Hesitation or surging
- Idle too high or too low
How to diagnose it
- Record freeze-frame data and identify from the vehicle's data list whether A and C refer to throttle-body or pedal signals; graph both while slowly moving the relevant control.
- Inspect the connector and wiring for the named A and C circuits for corrosion, moisture, pin damage, or contamination that could bridge adjacent terminals.
- Check each circuit's power, ground, and signal integrity at the sensor connector, following the wiring diagram and manufacturer's specification.
- Compare A and C live signal changes across the operating range and note whether one track is erratic or the relationship is consistently offset.
- If the circuits check out, test the sensor or assembly that carries the A/C tracks using the manufacturer's diagnostic procedure.
Common fixes
- Clean and secure corroded or contaminated A/C sensor connector terminals.
- Repair damaged wiring or poor connections affecting either the A or C signal.
- Replace the position-sensor assembly if one track is worn or the A/C relationship remains outside specification.
- Address a control-module fault only after the sensor and its circuits have been verified.
Can I keep driving?
Avoid driving if throttle response is reduced, surging, or unpredictable; the vehicle may limit power or enter limp mode. If response is normal, keep the trip short and cautious because the control module may further restrict throttle if the A/C signals diverge.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.