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 (VSS) Circuit: Notes
Vehicle Speed Sensor (VSS) is a magnetic reed switch located behind instrument panel. ECM provides battery voltage to switch, which toggles voltage high and low. This pulsed signal is used by ECM to determine vehicle speed (MPH or km/h).
- Code 24 will set if vehicle speed is zero MPH when:
- Engine is speed is 1500-4400 RPM.
- Vehicle speed is indicated at less than 3 MPH.
- Code 33 is not set.
- MAP sensor reading is less than 6.3 psi (43 kPa).
- Gear not in Park or Neutral (A/T only).
- All above condition 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.
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