U0118Lost Communication With Fuel Additive Control Module
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- U0118 concerns the fuel additive control module, which on some diesel cars meters a fuel-borne catalyst from a separate tank into the fuel. The additive lowers the temperature at which trapped soot burns in the particulate filter from above 600 °C to roughly 350–450 °C. If the engine controller no longer receives this module, it cannot be sure that dosing continues, and the regeneration strategy loses its footing. No manufacturer documents U0118 publicly; the text rests on CARB's requirement for a separate lack-of-communication code and on the known function of fuel-borne catalysts. Neighbours are U0467 (invalid data), P2584 (MIL request) and P2585 (warning lamp request) from the same module. Left unrepaired, the filter tends to clog, bringing a DPF warning and reduced power.
- What you may notice
- MIL and particulate filter warning
- Regeneration fails, filter loads up
- Reduced power in later stages
- Likely causes
- LikelyAdditive module unplugged or its fuse removed, e.g. after filter work
- PossibleCorroded connector at the additive tank or module under the vehicle
- PossibleDamaged CAN wiring to the additive module
- RareFuel additive control module internally faulty or not coded
- 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: €60 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.