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

P04D6

Exhaust Brake Input Circuit High

Same as P04D3 with the signal voltage above the plausible range. The exhaust control valve modulates exhaust backpressure or routing (EGR feed, sound, regen support); a malfunction shifts torque mapping and may trigger limp mode.

SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number4 / D6

Possible causes

  • Signal shorted to supply high
  • Connector pins corroded - high contact resistance low
  • Supply wire pinched against B+ source low

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