OBD-II code · Network (extended)

U3516 High Voltage System Interlock Circuit C Performance

HVIL loop C timing/pattern does not match expected behavior. 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 U3516?

The car may go into limp mode (reduced power). Get it diagnosed before a long trip.

Common causes

Most likelyIntermittent contact in HV connector
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 C

Related codes

Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.