U0168
Lost Communication With Vehicle Security Control Module
Communication / security
Generic OBD-II
Medium
What it means
U0168 means a module has lost communication with the vehicle security control module, which handles anti-theft and immobilizer functions. Depending on the vehicle, the engine may refuse to start (the immobilizer can't verify the key) or you may just get a security warning. If it starts and runs, the car generally drives normally.
Medium
Can I keep driving? Usually yes, but if the anti-theft/immobilizer function is affected the engine may not start; if it starts and runs, it should drive normally.
Common symptoms
What you'll notice
- Security or anti-theft warning light or message
- No-start or hard-start if the immobilizer isn't satisfied
- Key or fob not recognized
- Security module unreachable by a scan tool
Common causes
Most likely first
- Loss of power or ground to the security control moduleLikely
- Damaged wiring or connector at the moduleCommon
- CAN bus fault between the security module and other controllersCommon
- Failed vehicle security control moduleLess often
- Programming or key-sync issue after a repair or battery replacementLess often
How to diagnose & fix
Work through it in order
- Scan all modules and confirm the security module doesn't respond.
- Check the module's power, ground, and connector.
- Inspect the bus wiring between the security module and the network.
- Verify key/immobilizer programming if the module was recently serviced.
- Repair the wiring or replace and program the security module, then clear and re-test.
FAQ
Quick answers
Is it safe to drive with U0168?+
If it starts and runs, yes. But a security-module fault can prevent starting, so don't rely on it far from help until it's fixed.
Can I just clear U0168?+
You can, but it returns while the module is offline; anti-theft faults need the wiring or module repaired.
Related codes
Often seen with U0168
Read & clear U0168 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX