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

P00E4

Exhaust Heat Exchanger Exhaust Bypass Valve A Stuck Closed

The exhaust heat exchanger bypass valve A is stuck closed. Risk of overheating because exhaust always passes through the heat exchanger.

SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number– / E4

Possible causes

  • Valve stuck closed by carbon high
  • Carbon or debris buildup preventing free movement low
  • Component wear with age - mechanical play low

Inspection / repair

  • Difficulty: hard
  • DIY: shop recommended
  • Estimated cost: 200–1500 €
  • Estimated time: 2–6 h
  • Component: exhaust bypass valve a
  • Component: heat exchanger
  • MIL / check engine light
  • emissions-relevant
  • drive cycle required
  • limp mode possible

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