What it means
The reporting module has lost communication with the vehicle security control module. It sets this code when expected messages from that module are not received for a specified time.
How it works
The vehicle security control module manages security functions such as alarm or keyless-entry features and exchanges messages over the network. U0168 sets when the reporting module does not receive the expected security-module messages for a specified time; a power or ground fault, damaged CAN connection, low battery voltage, or module failure can cause the loss.
Common causes
Most likely first.
- Security module power or ground fault
- Damaged or corroded network wiring or connectors
- CAN bus short or open circuit
- Security module failure
- Low battery voltage
Symptoms
- Alarm or keyless entry functions fail
- Security warning light or message
- Other communication codes
How to diagnose it
- Scan all modules and review freeze-frame data for low voltage or other communication codes that could indicate a shared network fault.
- Check whether the alarm and keyless-entry functions work and note any security warning message.
- Inspect the security module's power, ground, CAN wiring, and connectors for corrosion, damage, looseness, or moisture.
- Test module power and ground under load against the manufacturer's specification, and check battery condition if low voltage was recorded.
- Test CAN communication at the security module and assess the module only after wiring and gateway routing have been checked.
Common fixes
- Secure or clean a loose or corroded security-module connector.
- Repair damaged CAN, power, or ground wiring to the module.
- Correct a weak battery or faulty supply connection if confirmed by testing.
- Repair gateway routing if network tests show messages are being misrouted.
- Replace the security control module only after its supplies and network wiring pass testing.
Can I keep driving?
If the fault is limited to alarm or keyless-entry functions, driving is generally possible, but access or security features may not work reliably. If starting or other vehicle systems are affected, have the communication fault diagnosed promptly.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.