Trouble code
C0040
Right Front Wheel Speed Sensor Circuit
What C0040 means
Invalid signal from the right front wheel speed sensor.
Symptoms you may notice
- ABS light
- Traction control light
- ABS inactive
Common causes, cheapest first
- Failed sensor
- Contaminated or damaged tone ring
- Chafed wiring
- Corroded connector
- Hub with integrated sensor failing
Before you buy anythingInspect the harness where it flexes with the suspension. Chafed wire is common and cheaper to repair than any part.
What to do next
- Confirm the code with your own scan tool, or have it read free at a chain parts store.
- Decode your VIN so you know your exact engine and build date.
- Work down the causes above from cheapest to most expensive.
- Search NHTSA for a recall or service bulletin covering this symptom on your vehicle.
- Read the brakes buying guide before ordering.
C0040 is a generic OBD-II code, standardized across every make and model sold in the US from 1996 onward. The meaning is the same on any vehicle; the specific part and its location are not.
Parts
Parts commonly needed for C0040
These go to Amazon. We earn a commission if you buy, at no extra cost to you — see our affiliate disclosure. Which one you actually need depends on diagnosis — read the note above first.
Confirm fitment against your VIN on the listing page before ordering. A part that matches your year and model can still be wrong for your build date or engine code.