Code result
P056D
Reductant Control Module System Voltage
Moderate severity
What it means
The reductant (AdBlue) control module reports its supply voltage outside the calibrated window. Reductant dosing is suspended until voltage returns to range, which can drive NOx emissions out of compliance.
Is it safe to drive?
Use caution
The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical.
Most likely causes
Supply voltage low
highOne of the most commonly reported causes for this code — check this first.
Related help
Get the full diagnosis
Add your vehicle and see step-by-step repair help, recalls, and TSBs in Wrenchify.
Diagnose P056D freeNo credit card required