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.
DTC U2001: Reduced System Function: Description
The ABS module incorporates a function for testing the vehicle on a dynamometer to prevent wheel speed sensor DTCs from setting during testing. The PCM sends a message to the ABS module when the vehicle is setup for testing. When the ABS module receives this message it knows to ignore discrepancies between the front and rear wheel speed sensors.
The ABS module exits the test mode automatically when the PCM sends the exit message, the ignition is set to OFF, either of the nondriven wheels exceeds 20 km/h (12 mph) or a wheel speed sensor DTC is detected on any wheel speed sensor.
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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.