U0168: Lost Communication With Vehicle Security Control Module
Other control units no longer receive messages from the Security Module.
High risk
Have it checked soon. The alarm, locking or starting may behave strangely.
Short answer · Can I keep driving with U0168?
Usually yes, with care. The alarm, locking or starting may behave strangely. Have the network and the module checked soon.
What does U0168 mean?
Code U0168 means a control unit expected regular messages from the Vehicle Security Control Module on the vehicle network and they stopped arriving. A power or ground fault at that module, a damaged network wire or corroded connector, low battery voltage or a failed module are typical causes.
What the car does when the code is set
The engine may not start, the alarm may behave strangely or the key may not be recognised.
How the system works
The immobiliser checks the code in the key and lets the engine control unit start the engine. The security module watches doors and sensors for the alarm. Both talk to other modules over the vehicle network.
Common symptoms
Possible causes
Listed without ranking. The cause on your car depends on make, engine and mileage — see the maker notes below.
- Low battery voltageSecurity and immobiliser modules are sensitive to voltage drops during starting.
- Power or ground fault at the moduleA blown fuse or a loose ground stops the module from answering.
- Network wiring or connector faultDamaged or corroded wires break the link to the module.
- Aftermarket alarm or trackerExtra devices wired into the security system can disturb it.
- Failed modulePossible, but check supply, ground and wiring first.
How it is diagnosed
- Check the batteryMeasure resting voltage and charge or replace a weak battery first.
- Try the spare keyIf the car starts with the spare key, the fault may be in the key rather than the module.
- Check fuses and groundsUse the fuse plan in the handbook for the security system.
- Scan all modulesA workshop checks whether the module answers and whether keys need to be relearned.Do not swap security modules between cars; they are usually coded to the vehicle and its keys.
Questions about U0168
Can a weak battery cause U0168?
Yes. Low voltage during starting can make modules drop off the network for a moment and store this code. Check the battery before replacing any module.
Will the car start with this code?
It may not. If the engine control unit cannot confirm the key with the immobiliser, it blocks starting.