Vehicle Speed Sensor A Range/Performance
What does P0501 mean?
The P0501 code means the vehicle's onboard diagnostic system has detected: Vehicle Speed Sensor A Range/Performance. This is a moderate severity code.
Common Symptoms
- Speedometer reading incorrectly or erratically
- Transmission shifting abnormally
- Cruise control not working
- ABS or traction control light on
- Check engine light illuminated
Probable Causes (Ranked by Likelihood)
- Faulty vehicle speed sensor (VSS) Very High
- Damaged or corroded VSS wiring or connector High
- Damaged tone ring or reluctor wheel on output shaft Moderate
- Transmission output shaft bearing wear affecting sensor gap Low
- PCM or instrument cluster fault Low
Step-by-Step Diagnostic Procedure
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Road test while monitoring VSS signal with a scan tool -- compare to GPS speed reading
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Inspect VSS connector for corrosion, bent pins, or loose connections
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Check VSS output signal with an oscilloscope -- should show clean square wave pattern
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Inspect tone ring on transmission output shaft for damaged or missing teeth
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Measure VSS resistance with a multimeter -- typical range is 190-250 ohms for magnetic sensors
Frequently Asked Questions
Can I drive with code P0501?
You can drive short distances, but be aware that the transmission may shift erratically and the speedometer may be inaccurate. Cruise control will likely not function. Avoid highway driving until repaired.
Where is the vehicle speed sensor located?
The VSS is typically located on the transmission output shaft housing, the transfer case, or on the rear differential. On newer vehicles, wheel speed sensors from the ABS system may also provide speed data to the PCM.
Can a bad speed sensor affect gas mileage?
Yes. The PCM uses vehicle speed data for fuel delivery calculations and transmission shift points. Incorrect speed data can result in improper shift timing and fuel delivery, reducing fuel economy.