U351DHigh Voltage System Interlock Circuit E
- Generic OBD-II code · Network
- Turns on the check-engine light
- Can trigger limp mode
- How the car detects it
- U351D covers a disturbed fifth interlock loop, circuit E, where the module cannot narrow the fault down. Five loops arise naturally if every protected housing gets its own circuit. A GM patent describes this: each high-voltage enclosure has a functional interlock tied to its access point, and the low-voltage signal inside only gets through while that opening is closed. Removing a cover is thus noticed by the circuit of that very housing. Which enclosure belongs to loop E is not published. Check covers, lids and their screws first, then the plugs of the housings involved; high voltage stays off until loop E is closed.
- What you may notice
- No ready mode after work on a high-voltage component
- High-voltage warning in the instrument cluster
- Likely causes
- LikelyCover of a high-voltage housing on loop E not fitted or not fully tightened
- PossibleInterlock contact or bridge in the cover bent or broken
- PossibleLoop E wiring damaged between housings
- RareEvaluating controller faulty
- Repair
- Hard · Usually a job for a workshop.Typical cost: €60 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.