P20C6Reductant Heater D Control Circuit Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- P20C6 is the functional check of heater D. FCA documents it for the 3.0 L EcoDiesel under the name Reductant Heater 4 Control Circuit Performance: bulletin 18-068-20 reflashed 2017 Ram 1500 engine computers that showed it, and a 2021 STAR case for 2020–2021 Ram 1500, Wrangler and Gladiator notes that it turns up mostly in severe cold, often without a defect. FCA asks technicians to confirm that ambient and tank temperatures read above 4 °C, inspect the supply line to the injector and run a dosing quantity test, which should capture 26–35 ml, before replacing anything; many returned pumps showed no fault. Deutz lists the code for its downstream line heater with an undetermined root cause (FMI 11). Only a failed dosing test or a leaking line justifies new parts.
- What you may notice
- Malfunction indicator lamp, mostly after very cold nights
- DEF system message, sometimes alongside pressure codes
- Often no noticeable change in how the vehicle drives
- Likely causes
- LikelyFalse detection in extreme cold with a still-frozen tank (FCA STAR S2118000006)
- PossibleOutdated engine control software (FCA 18-068-20)
- PossibleLeaking or blocked DEF supply line to the injector
- RareDEF pump unable to build pressure or injector delivering the wrong quantity
- 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: €0 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.