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

C0021

ABS Pump Motor Circuit Range/Performance

The pump motor responds, but its current draw or run time is outside the expected range. The control module suspects mechanical wear or hydraulic blockage.

SystemChassis
Typegeneric / SAE
GroupC0
Range / number– / 21

Possible causes

  • Pump worn, low delivery high
  • Hydraulic block contaminated with brake fluid debris medium
  • Sensor element aged beyond calibration window low

Symptoms

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

Inspection / repair

  • Difficulty: hard
  • DIY: shop recommended
  • Estimated cost: 400–1600 €
  • Estimated time: 2–5 h
  • Component: abs pump motor
  • Component: abs hydraulic block
  • Component: abs control module

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