U353FHigh Voltage System Interlock Circuit N Low
- Generic OBD-II code · Network
- Turns on the check-engine light
- Can trigger limp mode
- How the car detects it
- U353F covers a loop N value under the permitted minimum. The defect can sit inside a consumer rather than in the harness. For the Cummins battery electric systems BES CM2450 EV110B and EV111B, bulletin TSB250044 ties fault codes 8174 (interlock level too low or grounded) and 8175 to the electric air compressor: once the interlock contacts of the HV cable to the compressor pass, the measurement moves to the interlock pins of its low-voltage connector, and above 2 ohms (1 ohm in the first issue of February 2025) the compressor gets replaced. No maker documents U353F. While it is set, the vehicle is likely to lose high-voltage readiness.
- What you may notice
- High voltage switches off and stays off
- Interlock fault returns although all cable plugs test fine
- Auxiliary drive such as the air compressor not running
- Likely causes
- LikelyInterlock path inside an HV consumer such as an electric air compressor open or high-resistance
- PossibleHV cable plug on loop N not reconnected properly
- PossibleLoop N wire shorted to ground
- Repair
- Hard · Usually a job for a workshop.Typical cost: €100 – €6,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.