What Does U0108 Mean?
Network communication has been lost between the PCM and alternative fuel control module. This affects vehicles equipped with flex-fuel, CNG, propane, or hybrid fuel systems.
Common Causes
35%
Corroded or damaged wiring/connectors to alternative fuel module
30%
Failed alternative fuel control module
20%
CAN bus communication network fault
10%
Power supply or ground circuit failure
5%
Module software issue or programming error
Diagnostic Steps
1
Step 1: Verify power and ground circuits to alternative fuel control module
2
Step 2: Inspect module connectors for corrosion, damage, or water intrusion
3
Step 3: Test CAN bus signals at alternative fuel module connector
4
Step 4: Check for related DTCs that may indicate broader network or fuel system issues
5
Step 5: Test alternative fuel module functionality or replace if electrical tests pass
Estimated Repair Cost
$150 - $1,100
Parts + labor, varies by vehicle and location
Network communication has been lost between the PCM and alternative fuel control module. This affects vehicles equipped with flex-fuel, CNG, propane, or hybrid fuel systems.
The most common cause of U0108 (Lost Communication With Alternative Fuel Control Module) is: Corroded or damaged wiring/connectors to alternative fuel module
Typical repair costs for U0108 range from $150 to $1,100, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle may not switch between fuel types properly or may default to single fuel mode. Generally safe to drive but may strand driver if primary fuel is depleted.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to U0108 to identify the root cause.
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Quick Info
Category
Network
System
Alternative Fuel System / Network Communication
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
