OBD-II code · Chassis
C0040 Right Front Wheel Speed Sensor Circuit Malfunction
The ABS control module has detected a fault in the right front wheel speed sensor circuit. Loss of wheel speed information disables ABS and stability control, and a separate ABS warning lamp is illuminated.
Is it safe to drive with C0040?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyWheel speed sensor failed
- PossibleTone ring damaged or contaminated
- PossibleWiring break or chafe at wheel arch
- Less likelyWheel hub bearing with integrated sensor ring failed
Symptoms
- ABS warning light on
- ESC/stability control deactivated
- Possible reduced brake assist
- Speedometer may behave erratically
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.5–2.5 h
- Emissions test
- Usually unaffected
- Parts involved
- Wheel Speed Sensor, ABS Control Module, Tone Ring, Sensor Wiring
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.