P20C5Reductant Heater D Control Circuit/Open
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- 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.
- What you may notice
- Warning lamp in cold weather
- Dosing delayed while the downstream line thaws
- Likely causes
- LikelyHeating wire in the downstream DEF line burnt out or broken
- PossibleLoose or corroded heater D connector
- PossibleWire break in the harness to heater D
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €80 – €800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.