U0001
A faulty wheel speed sensor, A problem with the wheel speed sensor circuit, Reluctor issues, A problem with the ABS module.
- Audi
- Network
- Generic code
- Medium severity
How this code is built
- U
- SystemNetwork
- 0
- Defined bySAE, the same on every car
- 0
- AreaNetwork area 0
- 01
- FaultThe specific fault in that area
What it means
On this Audi, U0001 is listed as a wheel speed sensing fault: the ABS control unit is not getting a valid wheel speed signal from a sensor circuit, the reluctor it reads, or the ABS module is not processing the signal correctly. The control unit sets the code when a wheel speed signal is missing, implausible or disagrees with the other wheels. The exact wheel and test conditions depend on the model and year, so check the model-specific fault text.
Symptoms
- ABS warning light on
- Traction control or stability control warning light on
- Brake warning light on in some cases
- ABS, traction control or stability control not working
- Speedometer or cruise control behaving erratically on some models
- Brake pedal pulsing or feeling different under hard braking
Possible causes
- Faulty wheel speed sensorlikely
- Damaged, chafed or corroded wiring or connector in the wheel speed sensor circuitlikely
- Damaged, rusty or clogged reluctor (tone ring) or encoder hub bearinglikely
- Metal debris or dirt on the sensor tip, or incorrect sensor fitting or air gap after recent workpossible
- Worn wheel bearing causing excess play and an erratic signalpossible
- Poor power or earth supply to the ABS modulepossible
- Internal fault in the ABS modulerare
How to diagnose
- Read all stored codes from the ABS module and other control units, and note any wheel-specific codes and freeze frame data.
- Visually inspect each wheel speed sensor, its wiring along the suspension and the connectors for damage, chafing, corrosion or water ingress.
- Check the sensor tip and mounting for debris, looseness or damage, and check it is seated correctly.
- Inspect the reluctor ring or encoder for rust, cracks, missing teeth or contamination, and check the wheel bearing for play.
- With a scan tool that shows live data, compare all four wheel speeds on a road test and look for a wheel that drops out or reads incorrectly.
- Test the suspect sensor circuit for continuity, shorts and the correct resistance or signal using the model's workshop data.
- Check the ABS module power supplies, fuses and earths, and inspect its connector for corrosion.
- Only if everything else checks out, confirm the ABS module fault using manufacturer diagnostic procedures.
How to fix
- Replace the faulty wheel speed sensor with a correct part for the model.
- Repair or replace damaged wiring or connectors in the sensor circuit.
- Clean the sensor mounting, or replace a damaged reluctor ring or a hub bearing with a built-in encoder.
- Replace a worn wheel bearing.
- Repair power, earth or fuse faults feeding the ABS module.
- Repair or replace the ABS module only once it is confirmed faulty, then clear the codes and road test to confirm the fix.
Can I keep driving?
The car can usually be driven carefully for a short time because normal braking should still work, but ABS and stability control may not be available. Leave extra stopping distance, avoid wet or slippery roads where possible and get it checked soon.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.