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

C0020

ABS Pump Motor Circuit

The ABS control module detects an electrical fault in the pump motor circuit. Without a working pump, the system cannot build hydraulic pressure for ABS or stability control interventions and disables those functions.

SystemChassis
Typegeneric / SAE
GroupC0
Range / number– / 20

Possible causes

  • Pump motor seized after long inactivity high
  • Pump motor relay welded or open medium
  • Power supply connection corroded medium

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: 300–1400 €
  • Estimated time: 1.5–5 h
  • Component: abs pump motor
  • Component: abs control module
  • Component: pump motor relay
  • Component: power supply wiring

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