P05F8Reductant Heater Control Module Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P05F8 is the function check of the DEF heater control module: its feedback does not match the command – heating current or power, temperature rise, or an internal module fault. The code is documented for Chrysler's 3.0 L EcoDiesel in the 2014 Ram 1500 and Jeep Grand Cherokee: several bulletins list it together with the heater codes P20BA, P20BE and P20C2, and the fix in each case was only reprogramming the engine module – a diagnostic that was too sensitive rather than a hardware defect. It is not on Chrysler's inducement list. Ford checks the same function under heater plausibility codes. Thresholds for P05F8 are not published. If it returns after a software update, check the heater elements in tank and lines and the module supply (P05ED).
- What you may notice
- Check engine light on
- Usually no driveability issue
- DEF warning in cold weather, possible heater codes P20BA/P20BE/P20C2
- Likely causes
- LikelyEngine module software (Chrysler 3.0 L 2014: diagnostic revised by reflash)
- PossibleHeater control module faulty internally
- PossibleHeater element or line in tank or hose with abnormal current
- RareUnstable module supply or ground
- 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: €100 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.