P21AA

Reductant Level Sensor B Circuit Low

Severity

⚠️ Medium

Can you drive?

Yes, but get it checked soon

Approx. repair cost

$33–89 (est.)

Symptoms

Check Engine Light Is On
Low AdBlue message on the instrument panel
Possible engine power limitation
Increased fuel consumption
Increased NOx emissions

Causes

Low level of reductant (AdBlue) in the tank
Reductant level sensor fault B
Open or short circuit in the sensor circuit
Poor contact in the sensor connector
SCR control module malfunction

How to Fix

Check and, if necessary, add reductant (AdBlue)
Check the integrity of the sensor wiring and connectors
Test reductant level sensor B
If necessary, replace the level sensor
Check the operation of the SCR control module

Related codes

P21A9 P21AB P21AC