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 25, Code 26, Code 27, Code 28: Wheel Speed Acceleration Fault: Notes
Each wheel speed sensor generates a signal which is proportional to wheel speed. When ABS module detects speed signal change greater than 10 MPH while vehicle is moving, it disables Anti-Lock Brake System (ABS) and illuminates ABS light. See Fig 1 .
Code will set if wheel speed signal changes by greater than 10 MPH in 8 milliseconds. This code can be set any time vehicle is moving and not in ABS braking. Code 25/26/27/28 may be set together with Code 21/22/23/24. 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.