OBD-II code · Network (extended)
U3539 High Voltage System Interlock Circuit M
Generic fault on HVIL loop M. A communication loss with this module breaks any function relying on its data — diagnostic tools may show 'no response' and dependent modules can fall into limp mode.
Is it safe to drive with U3539?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyHV connector not fully mated
- Less likelyGateway module routing CAN messages incorrectly
- Less likelyCAN terminating resistor (120 Ω) drifted out of spec
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
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–5 h
- Emissions test
- Usually unaffected
- Parts involved
- Hvil Loop M, Hv Connectors
Related codes
- U3515High Voltage System Interlock Circuit C
- U3519High Voltage System Interlock Circuit D
- U351DHigh Voltage System Interlock Circuit E
- U3521High Voltage System Interlock Circuit F
- U3525High Voltage System Interlock Circuit G
- U3529High Voltage System Interlock Circuit H
- U352DHigh Voltage System Interlock Circuit J
- U3531High Voltage System Interlock Circuit K
- U3535High Voltage System Interlock Circuit L
- U353DHigh Voltage System Interlock Circuit N
- U3541High Voltage System Interlock Circuit O
- U3545High Voltage System Interlock Circuit P
- U3536High Voltage System Interlock Circuit L Performance
- U3537High Voltage System Interlock Circuit L Low
- U3538High Voltage System Interlock Circuit L High
- U353AHigh Voltage System Interlock Circuit M Performance
- U353BHigh Voltage System Interlock Circuit M Low
- U353CHigh Voltage System Interlock Circuit M High
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.