U0168
Lost Communication with Vehicle Immobilizer Control Module
The ECU cannot reach the immobilizer / vehicle security module. Engine start is usually blocked because the rolling code cannot be exchanged.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: hard
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
Common causes
Ordered by how often each turns out to be the cause.
- Immobilizer module unpoweredCommon
- Wiring or antenna ring damagedPossible
- Gateway module routing CAN messages incorrectlyLess likely
Parts involved
- Immobilizer Module
- CAN Bus Wiring
U0168 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.