P056D
Reductant Control Module System Voltage
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.
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.
Common causes
- high
Supply voltage low
One of the most commonly reported causes for this code — check this first.
Typical part cost: $130-550
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First things to check
- 1Confirm the code with a scan tool and check for additional related codes.
- 2Inspect the relevant sensors, wiring, and connectors for damage or corrosion.
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Related codes
See related trouble codes
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Frequently asked questions
What does P056D mean?
P056D means "Reductant Control Module System Voltage". It is a generic OBD-II code that points to a fault in the vehicle speed, idle control, auxiliary inputs.
What are the most common causes of P056D?
supply voltage low — these are the most commonly reported causes. Verify with a proper diagnosis before replacing parts, or use the Wrenchify app for a vehicle-specific diagnosis.
Can I keep driving with this code?
The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical. Use the Wrenchify app for a full diagnosis specific to your vehicle.
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