Invalid Test - Accelerator Pedal Input Open (Ford)
What does P1531 mean?
The P1531 code means the vehicle's onboard diagnostic system has detected: Invalid Test - Accelerator Pedal Input Open (Ford). This is a low severity code.
Common Symptoms
- Check Engine Light illuminated during self-test
- No drivability issues during normal driving
- Self-test reports invalid result
- Accelerator pedal signal reads open circuit during test
- No throttle response issues during driving
Probable Causes (Ranked by Likelihood)
- Accelerator pedal not fully released during self-test Very High
- Floor mat interfering with pedal return High
- Intermittent connection at the pedal position sensor Moderate
- Faulty accelerator pedal position sensor Moderate
- Wiring fault in the APP sensor circuit Low
Step-by-Step Diagnostic Procedure
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Ensure the accelerator pedal is fully released and unobstructed before running the self-test.
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Check that floor mats are not preventing the pedal from fully returning.
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Clear the code and rerun the self-test with the pedal properly released.
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If the code persists, check the APP sensor connector for looseness or corrosion.
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Monitor APP sensor voltage on a scan tool at rest and during pedal movement.
Frequently Asked Questions
Was the test run correctly?
P1531 is most often caused by the pedal not being fully released during the PCM self-test. Make sure the pedal returns completely and no floor mat is underneath it before running the test again.
Can a floor mat cause this code?
Yes. A floor mat that has slid forward and is blocking the accelerator pedal from returning fully is a common and easily overlooked cause of this code during self-test.
Does this affect driving?
No. P1531 is a self-test code only. If your vehicle drives normally with proper throttle response, the code was likely set during an improperly conducted test.