A short to voltage on the signal wire between accelerator pedal position sensor 1 and the ECM, often from chafed insulation or a pinched harness.; A faulty accelerator pedal position sensor 1 inside the pedal assembly, such as a worn potentiometer track or internal short.; Corroded, loose, or damaged electrical connectors at the pedal sensor or ECM, causing a poor ground reference.; An open ground circuit for the pedal sensor, which can make the signal voltage float high.; Water intrusion into the pedal sensor connector or harness, leading to corrosion and signal distortion.; A rare internal fault in the ECM driver circuit for the sensor reference voltage.

DTC codes / Volkswagen codes / P1631

P1631 · VolkswagenAccelerator Pedal Position Sensor 1 Signal Too High

Q: What does code P1631 mean?

Accelerator Pedal Position Sensor 1 Signal Too High. P1631 on Volkswagen vehicles means the engine control module (ECM) has detected an abnormally high voltage on the signal circuit from accelerator pedal position sensor 1, which typically indicates a short to voltage or an open ground reference. The ECM compares this signal against sensor 2 and expects a specific relationship, so a signal that stays too high will trigger the code and often force the engine into a reduced-power limp mode.

P1631 on Volkswagen vehicles means the engine control module (ECM) has detected an abnormally high voltage on the signal circuit from accelerator pedal position sensor 1, which typically indicates a short to voltage or an open ground reference. The ECM compares this signal against sensor 2 and expects a specific relationship, so a signal that stays too high will trigger the code and often force the engine into a reduced-power limp mode.

SystemPowertrain

Code typeVolkswagen specific

SeverityMedium

Fix difficultyIntermediate

AreaComputer and output circuits

Symptoms you may notice

The electronic throttle control (EPC) warning light or check engine light illuminates on the dashboard.
The engine may enter limp mode with severely reduced power and a maximum engine speed limit.
The accelerator pedal may feel unresponsive or the engine may idle at an elevated speed.
In some cases the engine may stall when coming to a stop or refuse to rev above idle.
Often no symptoms besides the warning light, especially if the fault is intermittent.
The cruise control system may become inoperative or disengage unexpectedly.

Common causes, most likely first

A short to voltage on the signal wire between accelerator pedal position sensor 1 and the ECM, often from chafed insulation or a pinched harness.
A faulty accelerator pedal position sensor 1 inside the pedal assembly, such as a worn potentiometer track or internal short.
Corroded, loose, or damaged electrical connectors at the pedal sensor or ECM, causing a poor ground reference.
An open ground circuit for the pedal sensor, which can make the signal voltage float high.
Water intrusion into the pedal sensor connector or harness, leading to corrosion and signal distortion.
A rare internal fault in the ECM driver circuit for the sensor reference voltage.

How to diagnose and fix it

Scan all modules for fault codes and record freeze-frame data to confirm P1631 is current and not a stored history code.
Inspect the accelerator pedal sensor connector and harness for corrosion, loose pins, or chafed wires, and repair as needed.
Measure the sensor 1 signal voltage and ground reference at the pedal connector with the key on, comparing against the manufacturer's specification.
Back-probe the signal wire at the ECM connector to check for a short to voltage while wiggling the harness to expose intermittent faults.
If wiring and connectors are good, replace the accelerator pedal assembly with the integrated sensor and clear codes.
After repair, perform a throttle adaptation or basic setting with a suitable scan tool and road-test to verify the code does not return.

Before you replace the accelerator pedal

A shorted or chafed signal wire in the harness near the pedal or under the dash is a more common cause than a failed pedal sensor on many Volkswagens.
The ECM expects sensor 1 and sensor 2 voltages to track in opposite directions, so a high signal 1 can also set companion codes for sensor 2 or a correlation fault.
Water ingress from a leaking windshield or cowl can corrode the pedal connector and cause intermittent high signal codes that only appear in wet weather.
A poor ground at the pedal sensor can make the signal voltage float high even though the sensor itself is good, so always load-test the ground circuit.
Clearing the code without repairing the underlying wiring fault often leads to a comeback because the ECM may relearn the fault after a few drive cycles.

Can I keep driving with P1631?

If the car is in limp mode with reduced power, drive only to a safe location or workshop and avoid highways; if the warning light is on but the car drives normally, keep speeds low and schedule diagnosis soon because the fault can become intermittent and suddenly trigger limp mode.

Tools that help

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Guidance is general and written for Volkswagen vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.