OBD-II code · Network
U0673 Lost Communication With Ion Sense Module
The vehicle bus reports loss of communication with the ion sense module (used for misfire/knock detection via ionisation current at the spark plug). Per-cylinder feedback is unavailable; misfire monitor falls back to crankshaft-deceleration logic only.
Is it safe to drive with U0673?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyBus wiring open or shorted
- PossibleModule without power or ground
- PossibleModule failed
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.5–3 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Ion Sense Module, Vehicle Bus Wiring
Related codes
- U0670Lost Communication With Fuel Temperature Sensor A
- U0671Lost Communication With Fuel Temperature Sensor B
- U0672Lost Communication With Engine Coolant Pump
- U0674Lost Communication With Wastegate Position Sensor B
- U0675Lost Communication With Turbocharger/Supercharger Speed Sensor A
- U0676Lost Communication With Fuel Level Sensor A
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.