A weak or failing vehicle battery that drops voltage during cranking and disrupts module communication; Corroded, loose, or damaged wiring at the immobilizer module connector or its ground point; A blown fuse or faulty relay in the circuit that powers the immobilizer control module; Water intrusion or physical damage to the immobilizer module or its harness; A failed immobilizer control module that no longer transmits on the network bus; A shorted or open controller area network bus wire between the immobilizer and other modules; A poor connection at the data link connector or a network gateway module that is not passing messages

DTC codes / U01xx · Lost communication with a control module / U0167

U0167Lost Communication With Vehicle Immobilizer Control Module

Q: What does code U0167 mean?

Lost Communication With Vehicle Immobilizer Control Module. U0167 means the engine control module or another network module has stopped receiving messages from the vehicle immobilizer control module over the controller area network bus. The computer detected a loss of communication, not necessarily a failed immobilizer, so the fault could be a wiring issue, a power or ground problem, or the module itself.

U0167 means the engine control module or another network module has stopped receiving messages from the vehicle immobilizer control module over the controller area network bus. The computer detected a loss of communication, not necessarily a failed immobilizer, so the fault could be a wiring issue, a power or ground problem, or the module itself.

SystemNetwork

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaLost communication with a control module

Symptoms you may notice

The security or immobilizer warning light stays on or flashes continuously
The engine cranks but will not start because the immobilizer is not authorizing fuel or spark
The engine starts and runs normally with only the warning light on, especially after a battery reconnect
Other unrelated warning lights appear because multiple modules share the same network bus
Intermittent no-start conditions that clear after the vehicle sits or the battery is disconnected
Remote keyless entry or push-button start functions become sluggish or stop working

Common causes, most likely first

A weak or failing vehicle battery that drops voltage during cranking and disrupts module communication
Corroded, loose, or damaged wiring at the immobilizer module connector or its ground point
A blown fuse or faulty relay in the circuit that powers the immobilizer control module
Water intrusion or physical damage to the immobilizer module or its harness
A failed immobilizer control module that no longer transmits on the network bus
A shorted or open controller area network bus wire between the immobilizer and other modules
A poor connection at the data link connector or a network gateway module that is not passing messages

How to diagnose and fix it

Perform a battery and charging system test, including a load test and a check for voltage drops during cranking
Inspect and clean the immobilizer module connector, checking for corrosion, pushed pins, or loose terminals
Check all fuses and relays that supply power to the immobilizer module and verify good grounds with a voltage drop test
Use a scan tool to read live network communication data and confirm whether the immobilizer module is present on the bus
Perform a wiggle test on the harness while watching live data to expose intermittent wiring faults
Check the controller area network bus resistance and voltage levels at the data link connector to rule out a bus short or open
If power, ground, and bus integrity are confirmed, replace and reprogram the immobilizer control module following the manufacturer's procedure

What most technicians miss on U0167

A weak battery is the most common cause of a stored U0167, and replacing the immobilizer module before load-testing the battery is a costly misdiagnosis.
The code does not always mean the immobilizer module is dead, because a single chafed bus wire or a corroded ground can produce the exact same communication loss.
After a battery replacement or jump-start, some vehicles set U0167 simply because the immobilizer module booted slower than the other modules, and the code clears after a few drive cycles.
A faulty ignition switch or push-button start module can interrupt power to the immobilizer module intermittently without setting a separate code, so check power delivery under load.
Water leaks into the kick panel or under-dash area often corrode the immobilizer connector and cause this code long before the module itself fails.

Can I keep driving with U0167?

If the engine starts and runs normally with only the warning light on, the vehicle is safe to drive to a repair shop, but avoid repeated short trips that cycle the immobilizer. If the engine cranks and does not start, do not keep cranking because the immobilizer is not authorizing the engine, and have the vehicle towed.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.