VOLVO
ABS-0021 - Right front wheel sensor. Faulty signal
System
Anti-lock Braking System (ABS)
Volvo models this fault code applies to
Applies to the following models:
9 modelsC70 Cabriolet (1998–2005), C70 Coupé (1998–2002), S60 (2001–2009), S70 (1997–2000), S80 (1999–2006), V70 (1997–2000), V70 (2000–2008), V70 XC (1998–2000), V70 XC / XC70 (2001–2007)
Show models by year and engine (9)
What does this fault code mean?
The right front wheel speed sensor is sending a signal, but its value does not match the other wheels. The ABS control module sees the wheel apparently stopping, turning too slowly or changing speed in an unnatural way. Because the circuit itself is intact, the cause is more often mechanical around the sensor, such as the brakes or the bearing. The equivalent code for the left front wheel is ABS-0011.
Possible causes
- The wheel has locked or stuck, for example from a sticking brake caliper
- Loose wheel speed sensor or dirt between the sensor and its mounting
- Damaged or dirty tone ring that the sensor reads
- Play in the wheel bearing or vibrations from the driveshaft
- Faulty wheel speed sensor or a faulty outlet valve in the ABS unit
What you can do
- 1Check that the brake caliper on the right front wheel is not sticking and the wheel spins freely
- 2Check the wheel bearing for play and noise
- 3Remove the wheel and check that the sensor sits flush against its mounting with no dirt or rust underneath
- 4Check that the tone ring is secure, complete, clean and undamaged
- 5Clear the code and road test; if it remains, have the sensor and ABS unit checked by a workshop
- 6ABS is safety-critical – avoid hard braking until the fault is fixed and do not let anyone unqualified work on the brake system
Symptoms you may notice3
- ABS and traction control warning lamps lit
- ABS does not work
- Traction control does not work
What the fault can affect2
- ABS and traction control are blocked
- The extra traction function is blocked on cars that have it
General guidance for car owners. Diagnosis on the car can point to a different cause.