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

P04D4

Exhaust Brake Input Circuit Range or Performance

Same as P04D3 with the signal in plausible range yet not matching expected behaviour - e.g. activation request without driver input or no response after a request.

SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number4 / D4

Possible causes

  • Signal implausible against driver action or bus high

Inspection / repair

  • Difficulty: medium
  • DIY: possible
  • Estimated cost: 120–450 €
  • Estimated time: 0.6–1.8 h
  • Component: exhaust brake request switch
  • 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