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

P203A

Reductant Level Sensor A Circuit

A general electrical fault is reported on DEF level sensor A — open, shorted, or out of plausibility. Some tanks use multiple level senders to cover irregular tank shapes; this is the primary one.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number– / 3A

Possible causes

  • Sender failed — float, swing arm, or rheostat high
  • Harness or connector fault 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: 120–800 €
  • Estimated time: 1–4 h
  • Component: reductant level sensor
  • Component: reductant tank
  • 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