P0502

Symptoms

• Check Engine Light Is On
• Speedometer does not work or shows zero speed
• Incorrect automatic transmission operation (delayed shifts)
• Disabling cruise control
• Possible ABS error

Causes

• Damaged or broken speed sensor
• Signal wire shorted to ground
• Destruction or damage to the toothed ring (tone ring)
• Severe contamination of the sensor-toothed ring gap
• Broken sensor cable screen
• Malfunction of the ECU or ABS

How to Fix

1. Read error codes with a scanner and check for ABS codes
2. Visually inspect the speed sensor and gear ring
3. Clean the sensor and tone ring area from dirt
4. Check the signal wire for short to ground with a multimeter
5. Check the sensor supply voltage (usually 5V or 12V depending on the type)
6. Check the sensor signal shape while moving with an oscilloscope
7. Replace the sensor or tone ring if it is faulty
8. Reset the error and check the speedometer readings

Related codes

Error P0502 by Vehicle Brand