What it means
The "C" channel signal is above the upper threshold — typically a short to positive or an open ground.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The position sensor E circuit is a separate signal path used by the throttle or accelerator pedal control system. P2125 sets when the module detects a general electrical fault in circuit E, such as a signal above its expected threshold from a short to positive or a lost sensor ground; confirm the vehicle's channel naming because sensor labels vary.
Common causes
Most likely first.
- Signal shorted to positive
- Sensor ground open
- Connector pins corroded - high contact resistance
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 related sensor codes, then check scan-tool data for the available position channels to identify whether the E signal is missing or implausible.
- Inspect the E circuit connector, signal wire, and sensor ground for loose pins, corrosion, chafing, or an open connection.
- Using the wiring diagram, check the E signal for a short to positive and verify the sensor supply and ground against the manufacturer's specification.
- Monitor E data while gently moving the harness to find a connection fault that comes and goes.
- If the wiring and connections are sound, test the position sensor assembly's E circuit according to vehicle-specific service information.
Common fixes
- Repair an E signal wire shorted to a positive supply or damaged insulation.
- Restore a sound sensor ground and correct corroded or loose connector terminals.
- Repair or secure harness sections that are chafed or strained.
- Replace the position sensor assembly if its E circuit fails testing with correct wiring and ground.
Can I keep driving?
A fault in the E signal circuit can make throttle response inconsistent or cause the control module to limit power. Avoid demanding acceleration and stop if the vehicle's response becomes unpredictable.
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.