U0668Lost Communication With Engine Oil Level Sensor Circuit
- Generic OBD-II code · Network
- How the car detects it
- Despite the word circuit in its name, U0668 concerns the data link to the oil level sensor, not a voltage fault. Sensors in the sump measure the oil height either thermally or by ultrasound; Hella's PULS type packs an ultrasonic transducer, a temperature sensor and an ASIC into one module that sends its result to the engine controller over a single signal line, and loss of supply or ground is one listed failure cause. When that signal no longer arrives or is unreadable, a separate lost-communication code can be stored. No manufacturer documents U0668 in public. Because oil level is normally not emission-relevant, CARB's rule on separate codes for silent digital inputs hardly applies. Electrical sensor faults are P250A to P250E, low or high oil P250F and P252F. Check the dipstick until fixed.
- What you may notice
- Oil level warning or service message in the display
- Oil level reading unavailable
- Likely causes
- LikelyMissing supply voltage or ground at the sensor
- PossibleSensor electronics failed or oil inside the housing
- PossibleCorroded or damaged connector or harness at the oil pan
- RareReceiving control unit input faulty
- Repair
- Easy · Often possible to do yourself.Typical cost: €40 – €400
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.