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

P20EF

Reductant Injection Valve Performance

The SCR reductant injection valve does not deliver the commanded amount of reagent. Causes include clogging by urea crystals, electrical faults or incorrect spray pattern.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number– / EF

Possible causes

  • Urea crystals in dosing valve high
  • Electrical fault in dosing valve medium

Symptoms

  • Check engine light or NOx warning on
  • AdBlue/DEF level or quality warning
  • Possible no-start countdown after ignore period
  • Failed emissions inspection (NOx)

Inspection / repair

  • Difficulty: hard
  • DIY: shop recommended
  • Estimated cost: 300–1500 €
  • Estimated time: 1–4 h
  • Component: def dosing valve
  • Component: def pump
  • 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