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

P050D

Cold Start Rough Idle

The ECU detects rough idle behaviour during the cold-start phase only. Once the engine has warmed up the issue disappears. Typically caused by injector deposits, low compression on one cylinder when cold, or sticky valve guides.

SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number5 / 0D

Possible causes

  • Injector tip coked - poor cold spray pattern high
  • Valve guide sticky when cold medium

Inspection / repair

  • Difficulty: medium
  • DIY: possible
  • Estimated cost: 80–600 €
  • Estimated time: 0.5–3 h
  • Component: fuel injectors
  • Component: cylinder compression
  • Component: valve guides
  • MIL / check engine light
  • emissions-relevant

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