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

P2DE8

Cold Start Engine Coolant Bypass Valve D Stuck Open

During cold start, the engine coolant bypass valve D is stuck in the open position. Coolant bypasses the warm-up loop.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / numberD / E8

Possible causes

  • Valve stuck in open position high
  • Actuator failed medium
  • Carbon or debris buildup preventing free movement low

Inspection / repair

  • Difficulty: medium
  • DIY: shop recommended
  • Estimated cost: 150–800 €
  • Estimated time: 1–4 h
  • Component: engine coolant bypass valve d
  • 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