OBD-II reference

All 9.533 generic OBD-II codes, explained in detail.

Causes, inspection steps and sources — a comprehensive DIY archive. Created and maintained with love for the detail. Good luck and have fun!

Chassis generic / SAE

C004B

Brake Fluid Level Sensor/Switch Circuit/Open

Open circuit on brake fluid level sensor or switch.

SystemChassis
Typegeneric / SAE
GroupC0
Range / number– / 4B

Possible causes

  • Wiring open high
  • Pin pushed back out of connector body low
  • Cracked solder joint inside the module or sensor low

Symptoms

  • ABS warning light on
  • ESC/stability control deactivated
  • Possible reduced brake assist
  • Speedometer may behave erratically

Inspection / repair

  • Difficulty: easy
  • DIY: possible
  • Estimated cost: 30–200 €
  • Estimated time: 0.3–1 h
  • Component: brake fluid level switch
  • MIL / check engine light

Sources

References

How to read OBD-II codes

The first letter names the vehicle system, the second digit distinguishes generic from manufacturer-specific, the remaining digits group fault area and number.

PPowertrain: engine, transmission, emissions
BBody: chassis trim, comfort, interior
CChassis: suspension, brakes, steering
UNetwork: CAN, control modules, communication