U0673Lost Communication With Ion Sense Module
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- After each spark, a small bias voltage across the plug gap lets the ignition system measure the current carried by ions in the burning mixture; Ford's patent US20170030322A1 shows such an ion sensing module passing this signal to the controller for combustion and knock assessment. U0673 means the engine controller no longer hears from that module. Stellantis lists U0673-00 among the MIL codes in a series of powertrain controller reflash bulletins for the 3.0 L Hurricane twin-turbo six (sales codes EFC and EFH): 18-022-25 Rev. A for the 2025 Wagoneer and Grand Wagoneer, 18-106-25 for the 2026 Ram 1500 and 18-071-26 for the 2025 Ram 1500. The stated cause is controller software, so updating it comes before replacing hardware.
- What you may notice
- Check engine light
- Other stored codes from the same software issue
- Usually no change in how the engine runs
- Likely causes
- LikelyPowertrain controller software (Stellantis Hurricane engines)
- PossibleBus, supply or ground wiring of the ion sense module faulty
- RareIon sense module internally failed
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Easy · Usually a job for a workshop.Typical cost: €0 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.