What does it mean?
P1634 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Acceleration Pedal Position Sensor 2 Signal Too High .
Symptoms
- MIL (check engine lamp) on with a reduced power warning
- Pedal position reported as applied with the pedal released, or the two channels disagreeing
- Engine held at a limited rpm or refusing to respond to the pedal
- Idle hanging high or the engine not returning to idle cleanly
- Cruise control unavailable
- Erratic acceleration and occasional stalling at a stop
Likely causes
- Sensor 2 signal wire shorted to battery positive or to the reference voltage
- Open or high-resistance ground for the second sensor channel
- Corrosion bridging pins in the pedal connector after water ingress
- Internal failure of the sensor 2 track inside the pedal module
- Harness chafed under the dash and touching a power feed
- Incorrect pedal assembly fitted with a different internal wiring arrangement
- Module input circuit fault, the least likely cause
How to fix it
- Read both pedal channels with the pedal released; sensor 2 should sit at its low rest value, not near the reference
- Unplug the pedal connector; if the reported voltage remains high, the fault is in the harness or module
- Test the ground for the second channel with a voltage-drop measurement, as an open ground drives the signal high
- Check the sensor 2 signal wire for a short to the reference voltage and to battery positive
- Inspect the connector and footwell for water, corrosion and damaged terminals
- Replace the accelerator pedal assembly once the wiring has tested good
- Run the pedal adaptation and verify both channels track correctly through the full travel