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!

Powertrain generic / SAE

P0571

Brake Switch "A" Circuit Malfunction

The brake light switch signal seen by the ECU is implausible — for example, both contacts active simultaneously, or no signal change despite the brake pedal being pressed (cruise control engages and disengages on this signal). On many cars also disables shift interlock.

SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number5 / 71

Possible causes

  • Brake switch failed (worn contacts, internal break) high
  • Switch misadjusted (does not actuate at correct pedal position) medium

Inspection / repair

  • Difficulty: easy
  • DIY: possible
  • Estimated cost: 20–150 €
  • Estimated time: 0.2–1 h
  • Component: brake light switch
  • Component: brake light switch wiring
  • 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