OBD-II code · Powertrain (generic, extended)
P221D Reductant Heater B Current Too High
Reductant Heater B Current Too High: the control module has detected this fault condition. The reductant (DEF/AdBlue) heater keeps the urea fluid from freezing; a fault can impair SCR dosing in cold conditions.
Is it safe to drive with P221D?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyElement partially shorted
Symptoms
- Check engine light or NOx warning on
- AdBlue/DEF level or quality warning
- Possible no-start countdown after ignore period
- Failed emissions inspection (NOx)
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.7–3 h
- Emissions test
- Likely to fail
- Parts involved
- Reductant Line Heater B
Related codes
- P214FReductant Heater A Current Too High
- P215FReductant Heater D Current Too High
- P221FReductant Heater C Current Too High
- P221ANOx Sensor 1/2 Correlation (Bank 1)
- P221BNOx Sensor 1/2 Correlation (Bank 2)
- P221CReductant Heater B Current Too Low
- P221EReductant Heater C Current Too Low
- P2220NOx Sensor Heater Control Circuit High (Bank 2)
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.