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 21, Code 22, Code 23, Code 24: Wheel Speed Equals Zero Mph: Notes
Each wheel speed sensor generates a signal which is proportional to wheel speed. If any wheel speed signal is less than 50 percent of other wheel speeds when vehicle is moving, ABS module disables Anti-Lock Brake System (ABS) and illuminates ABS light. See Fig 1 .
Code will set if one wheel speed signal is less than 50 percent of other wheel speeds. This code may set any time vehicle is moving faster than 5 MPH and is not in ABS braking. This code may be set together with Code 25/26/27/28. Failure may first appear to be an intermittent short or open which sets Code 25/26/27/28. Subsequent complete failure may then set code. Drive vehicle faster than 40 MPH to check for reappearance of failure.
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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.