What it means
The B 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 B and C provide related feedback from the throttle or pedal system, depending on the vehicle's design. P2137 sets when the control module detects that B and C no longer follow their expected relationship, which may result from a worn track or corrosion affecting either signal.
Common causes
Most likely first.
- Track B or C 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 B and C refer to throttle-body or pedal signals; graph both while slowly moving the relevant control.
- Inspect the connector and wiring for the B and C circuits for corrosion, moisture, damaged pins, or contamination that could affect contact between terminals.
- Check power, ground, and signal integrity for both B and C at the sensor connector, following the wiring diagram and manufacturer's specification.
- Compare B and C live signal changes over the operating range and identify whether one track sticks, jumps, or drifts away from the other.
- If the circuits are sound, test the position-sensor assembly carrying the B/C tracks using the manufacturer's procedure.
Common fixes
- Clean and secure corroded or contaminated B/C sensor connector terminals.
- Repair damaged wiring or poor connections affecting either the B or C signal.
- Replace the position-sensor assembly if either track is worn or the B/C relationship remains out of specification.
- Repair a control-module fault only after the sensor and wiring tests pass.
Can I keep driving?
Avoid driving if throttle response is reduced or inconsistent; limp mode or limited acceleration may occur. If symptoms are absent, drive cautiously only as needed for diagnosis, since a larger B/C disagreement can cause the module to restrict throttle.
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.