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.

Real-world scan data

Seen in

363

scans in the past year

Found in

0.1%

of scans

0.1%

of scans that found faults

Appears alongside · share of U0168 scans

U0100in 27.8% of scans

U0155in 26.2% of scans

U0101in 20.9% of scans

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

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.

Read & clear U0168 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX