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 24, Vehicle Speed Sensor Circuit
ECM supplies a B+ signal to Vehicle Speed Sensor (VSS). While vehicle is moving, a reed switch inside VSS will open and close, toggling B+ signal high and low.
- If speedometer is inoperative, this could cause Code 24.
- Checks if ECM is supplying B+ to VSS.
- The VSS on the back of instrument panel will toggle B+ signal high and low. Code 24 will set under the following conditions: fuel is cut for 4 seconds or longer, engine speed is less than 4000 RPM, and vehicle speed is less than one MPH.
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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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