Powertrain, generic (extended)

P20C5 Reductant Heater D Control Circuit/Open

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P20C5 covers an open control circuit in reductant heater D, the fourth heating element that only a few SCR layouts carry. Deutz is the one maker found that publishes the code: in its EMR5/MD1 fault list D is the downstream line heater, and P20C5 maps to SPN 520471 with FMI 5, an open or too little current. FCA's 3.0 L EcoDiesel also has a heater 4 (see P20C6), but no public document names P20C5 for it, and vehicle makers give no thresholds. Detection most likely follows the method GM documents for its heaters 1–3, which pinpoints an open with the output switched off, Type A once 2 s have passed. CARB requires output components to be checked for circuit faults. A broken wire, a loose connector or a burnt-out element in the heated downstream line are the likely causes.

Likely causes

Heating wire in the downstream DEF line burnt out or broken
Loose or corroded heater D connector
Wire break in the harness to heater D

Symptoms

  • Warning lamp in cold weather
  • Dosing delayed while the downstream line thaws

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–800
Time0.5–3 h

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

Parts involved

reductant line heater d

Related codes

P20C6P20C7P20C8P20C1P20BDP20B9

References: serdia.deutz.com, law.cornell.edu, gsi.ext.gm.com.