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

P2557

Engine Coolant Level Sensor/Switch Circuit Range/Performance

The coolant level sensor is electrically intact, but the readings are implausible — for example a level that does not move at all over many drive cycles, or jumps that cannot match real coolant loss. Often a stuck float, contaminated electrode or air-locked sensor.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number5 / 57

Possible causes

  • Stuck float high
  • Trapped air around the sensor medium
  • Sensor element aged beyond calibration window low

Inspection / repair

  • Difficulty: easy
  • DIY: possible
  • Estimated cost: 40–250 €
  • Estimated time: 0.3–1.5 h
  • Component: coolant level sensor
  • Component: cooling system
  • 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