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.
Code 42 - Noise On Vehicle Speed Sensor Input: Description
PCM detects vehicle speed by counting pulses from Vehicle Speed Sensor (VSS). PCM can detect incorrect input signals (noise) by comparing input value to normal data in memory. PCM sets code 42 if VSS input is incorrect or if VSS indicates vehicle speed is greater than 15 MPH.
- This step checks for connector problems at PCM.
- This step checks PCM for internal problems.
- This step checks for connector problems at VSS.
- This step checks each circuit for any visual problems.
- This step lists other possible causes of code 42.
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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.
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