OBD-II code · Chassis
C004B Brake Fluid Level Sensor/Switch Circuit/Open
Open circuit on brake fluid level sensor or switch.
Is it safe to drive with C004B?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyWiring open
- Less likelyPin pushed back out of connector body
- Less likelyCracked solder joint inside the module or sensor
Symptoms
- ABS warning light on
- ESC/stability control deactivated
- Possible reduced brake assist
- Speedometer may behave erratically
Repair at a glance
- Difficulty
- Easy
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.3–1 h
- Emissions test
- Usually unaffected
- Parts involved
- Brake Fluid Level Switch
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.