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

P0478

Exhaust Pressure Control Valve A High

Exhaust pressure control valve A drive line stuck high — short to B+.

SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number4 / 78

Possible causes

  • Short to B+ high

Inspection / repair

  • Difficulty: medium
  • DIY: shop recommended
  • Estimated cost: 120–800 €
  • Estimated time: 0.7–3 h
  • Component: exhaust pressure regulator
  • MIL / check engine light
  • emissions-relevant

Sources

References

sae:J2012

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