VOLVO
ABS-0040 - Right rear wheel sensor. Signal missing. Intermittent fault
System
Anti-lock Braking System (ABS)
Volvo models this fault code applies to
This fault code has different meanings depending on model, model year or engine. Select the meaning that applies to your car.
Applies to the following models:
5 modelsC70 Cabriolet (1998–2005), C70 Coupé (1998–2002), S70 (1997–2000), V70 (1997–2000), V70 XC (1998–2000)
What does this fault code mean?
The ABS control module has at times lost the signal from the wheel speed sensor on the right rear wheel. The fault is intermittent, meaning it is sporadic and may not be present right now. It can be caused by a temporary poor contact or a break in the wiring. The equivalent code for the left rear wheel is ABS-0030.
Possible causes
- Contact resistance in the connections
- Open circuit or short to ground or supply voltage in the sensor supply
- Signal wires briefly shorted to each other
- Signal wire briefly shorted to ground or supply voltage, or a temporary open circuit
- Faulty wheel speed sensor or, less commonly, a faulty control module
What you can do
- 1Read the code, clear it and road test to see whether it returns
- 2Check the connector at the right rear wheel sensor for looseness, moisture and oxidation
- 3Check the connector at the module and the wire between the module and the sensor
- 4Follow the cable from the sensor and look for chafing and pinched sections
- 5If the fault remains or returns often, have a workshop check the wiring with diagnostic equipment
- 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 notice4
- ABS and traction control warning lamps lit
- Brake system warning lamp lit
- ABS and traction control do not work
- The ABS warning lamp may only go out some way into the next drive
What the fault can affect2
- ABS and traction control are blocked
- Brake force distribution is disabled if two or more sensors stop working
General guidance for car owners. Diagnosis on the car can point to a different cause.