U0167: Lost Communication With Vehicle Immobilizer Control Module

What it means

A control module is not receiving expected messages from the Vehicle Immobilizer Control Module. Starting authorization may be affected, depending on the vehicle; the code alone does not identify why communication was lost.

At a glance

• Usually lights the warning light of the system that lost communication

How it works

The vehicle immobilizer control module checks key authorization and communicates the result to other modules, often through the vehicle network. U0167 sets when a receiving module misses the expected immobilizer messages; lost module power, an antenna-ring fault, CAN trouble, or gateway routing can disrupt starting authorization.

Common causes

Most likely first.

1. Immobiliser module unpowered
2. Immobiliser antenna ring failed
3. Gateway module routing CAN messages incorrectly

Symptoms

• Immobilizer warning or message
• Engine may not start if starting authorization is affected
• Other communication codes

How to diagnose it

1. Check whether the engine starts and note any immobilizer warning, then scan all modules for related security, key, and communication codes.
2. Review freeze-frame or event data for low voltage and compare whether other modules lost communication at the same time.
3. Inspect the immobilizer module's power, ground, CAN wiring, connectors, and key antenna-ring connections for damage, looseness, or corrosion.
4. Test immobilizer-module power and ground under load against the manufacturer's specification and check the antenna-ring circuit using vehicle-specific procedures.
5. Test CAN communication and gateway routing at the immobilizer module before considering module replacement or key-system programming.

Common fixes

• Restore a weak battery or poor supply connection if low voltage is confirmed.
• Secure or clean loose or corroded immobilizer-module or antenna-ring connections.
• Repair damaged power, ground, or CAN wiring to the immobilizer system.
• Repair or replace a failed antenna ring if its circuit tests identify it as faulty.
• Replace or reconfigure the immobilizer module only after its circuits and network path are verified.

Can I keep driving?

If the engine starts normally, avoid switching it off in an isolated place until the fault is checked, because starting authorization may fail intermittently. If it will not start or shows an immobilizer warning, arrange diagnosis rather than repeatedly attempting to start it.