Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC P0502: VSS Circuit - Low Input (M/T): Description
Output Speed Sensor (OSS) produces an AC voltage of different amplitude and frequency depending on the velocity of the output shaft. OSS produces signal from evenly spaced machined notches on transaxle final drive assembly. OSS produces a readable AC voltage signal when speed is more than 3 MPH. OSS signal is sent to ECM, which is used to determine vehicle speed. DTC sets when ECM does not detect an OSS signal for a certain length of time.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.