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
The Vehicle Speed Sensor (VSS) is a reed switch located behind instrument panel. The ECM provides battery voltage to switch, which toggles the voltage high and low. This pulsed signal is used by ECM to determine vehicle speed (MPH or km/h).
- Code 24 is set if vehicle speed equals 0 MPH under the following conditions:
- Engine speed is between 1500-4400 RPM.
- VSS indicates less than 3 MPH.
- No Code 33 stored in memory.
- MAP reads low voltage with high vacuum (low load condition).
- Gear is not in Park or Neutral.
- All conditions are met for 5 seconds.
These conditions are met during a road-load deceleration. Disregard Code 24 that is set when drive wheels are not turning.
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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.