Powertrain, generic (extended)

P215E Reductant Heater D Current Too Low

Check engine lightOn

EmissionsRelevant

Drive cycleRequired

Limp modePossible

P215E says the fourth DEF heating element, heater D, drew less current than expected while it was switched on, so it is probably not warming the fluid. Which element carries the letter D depends on the maker; many SCR systems stop at three. No maker documents P215E publicly. GM's 2025 Duramax tables and Ford's 2023 diesel summary check only heaters A to C; GM flags their currents below 0.75 A across 40 readings, one per tenth of a second, as Type A; Ford watches power and current during each heating cycle. GM bulletin 21-NA-149 does show a heater D on the 3.0 L LM2, but only with circuit codes P20C5 and P20C8. The usual causes are an open or burnt element, high resistance at the connector or a missing heater feed. P215F is the high-current partner, P20C5 to P20C8 the control-circuit faults. In frost the fluid may thaw late.

Likely causes

Heating element D open or burnt through, often inside a heated line or pump assembly

Corroded or loose pins at the heater D connector limiting current

Heater feed fuse or relay open, so the element gets no voltage

Weak heater output stage in the engine or DEF control module

Symptoms

Check engine light together with a DEF or emission system message
Dosing starts late or not at all after cold starts in frost
Restart countdown or speed limitation if the fault stays active

Repair estimate

DifficultyMediumWorkshop job

Parts and labour€80–900

Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

reductant line heater d

References: law.cornell.edu, gsi.ext.gm.com, fordservicecontent.com, static.nhtsa.gov.