P202CReductant Tank Heater Control Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P202C is the high-side fault of the DEF tank heater circuit: the module sees a value above the allowed range, as when the wire touches battery positive or an element that conducts far too well. On the Touareg 3.0 TDI of model year 2014, Volkswagen flags it when the element's conductance at the start of heating exceeds 0.62 S, below roughly 1.6 Ω, which hints at an internal short. On 2025 Ram 2500 to 5500 with the 6.7 L Cummins, Chrysler's bulletin 08-076-26 lists P202C next to other DEF heater and pressure codes and cure them with new software for the DEF control unit; there the fault came from calibration, not from hardware. With a real short the fuse may blow or the driver protect itself, so the tank stays unheated. In winter the system may then warn and count down to a speed limit.
- What you may notice
- Malfunction indicator lamp on
- Service DEF message, later speed limited
- Heater fuse may blow
- Likely causes
- PossibleDEF control unit calibration (software update on some models)
- PossibleHeater element with internal short, resistance too low
- RareHeater control wire shorted to battery voltage
- 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: €50 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.