Code result
P20B5
Reductant Metering Unit Heater Control Circuit/Open
Moderate severity
What it means
The control circuit for the heater inside the DEF metering unit is open — winter operation cannot keep the dosing block above freezing.
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
Heater winding open
highOne of the most commonly reported causes for this code — check this first.
Pin pushed back out of connector body
lowLess common, but worth ruling out after the more likely causes.
Cracked solder joint inside the module or sensor
lowLess common, but worth ruling out after the more likely causes.
Related help
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