U3531High Voltage System Interlock Circuit K
- Generic OBD-II code · Network
- Turns on the check-engine light
- Can trigger limp mode
- How the car detects it
- U3531 stands for an unspecified fault on interlock circuit K, the tenth loop. An interlock need not be a dedicated wire pair. For hybrid trucks, International patented running the hybrid CAN bus through the same connector as the power cable: once the plug is parted, data traffic on that bus stops and one terminating impedance drops out, and a traffic detector then opens an interrupter in the high-voltage feed. A loop K built along these lines would react to a dead or disturbed bus section as well as to an open plug, so network faults stored in the same controllers deserve attention. No maker discloses the members of loop K. High voltage stays blocked while the fault is active.
- What you may notice
- No ready mode or one high-voltage branch unavailable
- Network or communication codes stored alongside
- High-voltage system warning in the instrument cluster
- Likely causes
- LikelyConnector in loop K not fully latched
- PossibleCommunication line routed with loop K interrupted or disturbed
- PossibleLoop K wiring damaged
- RareController monitoring loop K faulty
- Repair
- Hard · Usually a job for a workshop.Typical cost: €80 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.