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

P01F0

Coolant Temperature Relapsed Below Diagnostic Monitoring Temperature

Coolant temperature dropped below the diagnostic monitoring threshold after warm-up. Often thermostat stuck open or stuck-open coolant heater bypass.

SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number1 / F0

Possible causes

  • Thermostat stuck open high

Inspection / repair

  • Difficulty: medium
  • DIY: possible
  • Estimated cost: 60–400 €
  • Estimated time: 0.5–3 h
  • Component: thermostat
  • Component: coolant circuit
  • MIL / check engine light
  • emissions-relevant
  • drive cycle required

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