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P0502 OBD-II Trouble Code: Vehicle Speed Sensor Low Input

Check Engine Light

Vehicle Speed Sensor Low Input

What the P0502 code means

The P0502 trouble code means that the Engine Control Module (ECM) has detected a different reading of speed between the vehicle speed sensor and the wheel speed sensors.

What are the causes of the P0502 code?

  • A faulty vehicle speed sensor
  • Damaged wiring or connectors in the vehicle speed sensor circuit
  • Multiple faulty wheel speed sensors/ hub bearings
  • Broken ABS tone rings
  • A faulty powertrain control module
  • Incorrect size wheels or tires
  • A faulty instrument cluster

What are the symptoms of the P0502 code?

Other than a Check Engine Light and an inaccurate speedometer, there should be next to no symptoms associated with this trouble code.

How does a mechanic diagnose the P0502 code?

The most common cause of the P0502 trouble code is a faulty vehicle speed sensor so the mechanic would likely start by locating it. If the sensors wiring and connector seem to be in good condition, the mechanic would then test the vehicle speed sensor using the manufacturer’s recommended procedure.

The mechanic would also check all the wheels and tires to ensure they are the correct size. A check of the suspension on all four wheels would be performed to check the tone rings and wheel speed sensors.

Finally, if no other issues are found, the ECM would be tested and parts would be replaced at the customer’s request.

Common mistakes when diagnosing the P0502 code

A common mistake that could be made when this trouble code is stored would be to replace the vehicle’s instrument cluster due to the inaccurate speedometer. The instrument cluster receives a signal from the vehicle speed sensor so it is important to check there first.

How serious is the P0502 code?

This trouble code is not very serious at all due to the fact that it does not cause any drivability issues. The only thing to worry about with this trouble code is getting a speeding ticket due to the inaccurate speedometer.

What repairs can fix the P0502 code?

Repairs that can fix the P0502 trouble code may include:

Additional comments regarding the P0502 code?

Many people like the looks of very large wheels on their vehicle. However, they do not realize the potential damages this can cause to the vehicle. The ride quality suffers, the wheels are more susceptible to damage from pot-holes, the brakes do not work as well, the steering is not as predictable, and codes such as the P0502 may be stored.

Need help with a P0502 code?

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The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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