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

C05A8

ABS Pump Motor Supply Voltage B Circuit Range/Performance

ABS pump motor supply B drifts or fluctuates. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.

SystemChassis
Typegeneric / SAE
GroupC0
Range / number5 / A8

Possible causes

  • Connector with high resistance high
  • Sensor element aged beyond calibration window low
  • Sensor mounting loose - signal damping low

Symptoms

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

Inspection / repair

  • Difficulty: medium
  • DIY: possible
  • Estimated cost: 30–400 €
  • Estimated time: 0.5–2 h
  • Component: abs pump supply b
  • 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