OBD-II code · Chassis
C0504 Left Front Wheel Speed Sensor A Intermittent/Erratic
Intermittent or erratic signal from left-front wheel speed sensor A. Wheel-speed signals feed ABS, ESC, traction control, transmission and odometer — a single dropped signal disables all of these safety functions until repaired.
Is it safe to drive with C0504?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyConnector loose or chafed wiring
- Less likelyConnector with intermittent contact under vibration
- Less likelyHarness routed against vibrating component
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 h
- Emissions test
- Usually unaffected
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Wss Lf, Sensor Wiring
Related codes
- C0655Left Front Wheel Speed Sensor B Intermittent/Erratic
- C0501ESC Active Performance
- C0502Left Front Wheel Speed Sensor A Circuit Low
- C0503Left Front Wheel Speed Sensor A Circuit High
- C0505ESC Switch Circuit
- C0506Right Front Wheel Speed Sensor A Circuit/Open
- C0507Right Front Wheel Speed Sensor A Range/Performance
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.