Accelerator Pedal Position Sensor 1 Signal Invalid
The engine control module (ECM) is receiving an invalid signal from the accelerator pedal position sensor 1.
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What it means (plain English)
The computer is getting a faulty signal from the accelerator pedal sensor, which tells the engine how much power to produce based on how far you push the pedal.
What the computer is actually seeing
The ECM expects a signal between 0.5V (idle) and 4.5V (full throttle) from the accelerator pedal position sensor; anything outside of this range is flagged as invalid.
What a healthy reading looks like
0.5V to 4.5V from sensor under normal operation; should increase smoothly as the pedal is pressed.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Inspect the wiring and connectors at the accelerator pedal position sensor for damage or corrosion. Decision: If damaged, repair or replace. If not, proceed to step 2.
- 22. Measure the voltage at the accelerator pedal position sensor connector with the key ON (engine OFF). You should see a voltage between 0.5V and 4.5V. Decision: If outside this range, replace the sensor. If within range, move to step 3.
- 33. Check the ground signal of the sensor connector. It should be near 0V (close to battery ground). Decision: If not, fix the ground issue. If fine, check ECM for faults.
Common causes
- Damaged wiring or connectors to the accelerator pedal position sensor
- Faulty accelerator pedal position sensor itself
- ECM software error
- Poor ground from the ECM
Typical repair cost
$$-$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's moderate severity; you can drive it for a short time, but fix it soon as it affects throttle response.
Will this code come back after clearing it?
If the underlying issue isn’t fixed, yes, it will return.
Why does this code often pair with SPN 3383?
SPN 3383 indicates a similar issue with pedal sensor 2, which often fails alongside sensor 1.
Working a real vehicle right now?
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