P2127Powertrain
Powertrain · SAE
Accelerator Pedal Position Sensor E — Low Signal
Meaning
The signal voltage of the accelerator pedal position (APP) sensor track E is below the minimum acceptable threshold (typically < 0.2 V). Track E is the second redundant channel of the pedal sensor; a low signal indicates a short to ground, open circuit, or internally failed sensor.
Common causes
- Short to ground on the APP track E signal wire
- Open circuit in the track E wiring
- Internal short to ground in the APP sensor on track E
- Corroded or loose pedal sensor connector
- Failed 5 V reference supply for the E circuit
Symptoms
- Check-engine light (MIL) on
- Limp-home mode with throttle limitation
- Absent or severely reduced accelerator response
- Often associated code P2138 (implausible D/E correlation)
- Engine speed fixed at idle in some cases
Severity
High: loss of APP E signal eliminates pedal sensor redundancy and activates limp-home mode.
What to do
- Measure APP E signal voltage at the connector (0.5–4.5 V with pedal released/fully depressed)
- Disconnect the sensor and measure voltage on signal wire E: if still low, short to ground in the wiring
- Verify the 5 V reference supply
- Inspect the pedal sensor connector for corrosion and intermittent contacts
- Replace the APP sensor if the short is internal