What it means
A control module has lost communication with the fuel cell control module. Fuel-cell system operation may be affected on vehicles equipped with one.
How it works
The fuel cell control module manages or reports fuel-cell system operation on vehicles equipped with a fuel-cell powertrain. This code sets when another module no longer receives its expected messages, so fuel-cell operation may be restricted or unavailable.
Common causes
Most likely first.
- Loss of module power or ground
- Open, shorted, or damaged communication wiring or connector
- Module or gateway fault
Symptoms
- Fuel-cell system warning
- Fuel-cell operation may be limited or unavailable
- Communication faults in other modules
How to diagnose it
- Scan all modules for U0118 and related fuel-cell or network codes, recording which modules have lost contact with the fuel cell control module.
- Review freeze-frame data and warning history for clues about whether the loss occurred at startup or while operating.
- Inspect accessible fuel cell control module connectors and harness sections for looseness, corrosion, moisture, or physical damage.
- Check the module's low-voltage power and ground circuits against the manufacturer's specification using the correct wiring diagram.
- Test the communication wiring to the fuel cell control module for opens, shorts, or poor connections according to the vehicle's procedure.
- If power, ground, and network circuits pass, investigate gateway routing or a failed control module with vehicle-specific diagnostics.
Common fixes
- Reconnect or repair a damaged or corroded connector at the fuel cell control module.
- Repair a failed low-voltage feed or ground to the module.
- Repair an open, short, or poor connection in its network wiring.
- Repair a confirmed gateway issue or replace and configure the fuel cell control module if testing confirms failure.
Can I keep driving?
If the fuel-cell system warning is on or propulsion is limited, avoid relying on the vehicle for a trip where power could be needed and stop if it cannot operate predictably. Have the fault assessed before continued use if fuel-cell operation is unavailable.
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.