AdBlue tank actually low or empty; Faulty level sensor, often integrated in the tank heater and sender unit; Wiring or connector faults; Frozen or crystallised AdBlue affecting the sensor.

SCR / AdBlue

P203F Reductant (AdBlue/DEF) Level Too Low

Q: What does P203F mean?

Reductant (AdBlue/DEF) Level Too Low. The ECU monitors the AdBlue (DEF) tank level through the level sensor. P203F is set when the reported level falls below the minimum required for dosing.

The ECU monitors the AdBlue (DEF) tank level through the level sensor. P203F is set when the reported level falls below the minimum required for dosing.

Common causes

AdBlue tank actually low or empty
Faulty level sensor, often integrated in the tank heater and sender unit
Wiring or connector faults
Frozen or crystallised AdBlue affecting the sensor

Typical symptoms

Low AdBlue warning and check engine light on
Countdown to engine start restriction
Reduced power or speed limitation on some vehicles

P203F and NuoVolta

If the SCR/AdBlue system has been removed or disabled for off-road or motorsport use, where permitted by law, the NuoVolta AdBlue / SCR / NOx Removal solution adjusts the ECU calibration and the DTC removal feature can disable this code. On a working system, top up AdBlue and check the level sensor first.

AdBlue / SCR / NOx Removal Available for 121 ECUs

Related codes

P2047Reductant (AdBlue/DEF) Injector Circuit/Open (Bank 1 Unit 1) P20E8Reductant (AdBlue/DEF) Pressure Too Low P20EESCR NOx Catalyst Efficiency Below Threshold (Bank 1)

Diagnose and repair real faults first. Removing or disabling emission systems is only permitted where allowed by law, for example for off-road or motorsport use.