U0119: Lost Communication With Fuel Cell Control Module
Do not keep driving
Stop somewhere safe, switch off, and arrange recovery rather than driving on. Do not open the bonnet or go near the tanks.
This is a hydrogen fuel cell vehicle, and the computer that manages the fuel cell has stopped communicating. Because the car can no longer confirm the hydrogen supply is closed or the stack has stopped generating, the only safe thing it can do is shut everything down — which is why it has probably stopped or will not start.
Two hazards make this different from an ordinary breakdown. The system runs at several hundred volts, and it stores hydrogen at very high pressure. A hydrogen leak cannot be seen or smelt and burns with a flame that is almost invisible in daylight.
So: if you hear hissing, smell anything unusual, or see a hydrogen warning, get everyone out of the vehicle, move well away from it, and call for help. Do not investigate.
Tell the recovery operator what the vehicle is when you call, and make sure it goes to a workshop with specific hydrogen fuel cell training. A general garage should not open this system.
What this code means
The fuel cell control module has stopped being heard from. The general reasoning is at U0100, and the safety paragraph at U0468 comes before anything on this page — several hundred volts of direct current and hydrogen stored at very high pressure, neither of which is a general workshop's work.
Silence here is treated far more seriously by the vehicle than bad data, and the reason is worth understanding.
A stack controller that is reporting implausibly can still be told to shut down in an orderly way. A stack controller that has stopped answering cannot be told anything — so the vehicle has no way to confirm that hydrogen supply is closed, that the stack is not still generating, or that its temperature is under control. The only safe response to that is to isolate everything immediately.
Which is why this is one of the corpus's rare is_drivable: false codes. The vehicle will normally shut the stack down, open the high-voltage contactors and stop, or refuse to start at all. Expect to be recovered rather than to drive on, and treat a vehicle that does still move as running on a small buffer battery with no way to replenish it.
Do not attempt any inspection. Hydrogen leaks are invisible, odourless, and burn with a flame that is nearly impossible to see in daylight. If there is hissing, an unusual smell, or a hydrogen warning, get everyone out, move well away, and call for professional help rather than opening anything.
Recovery should go to a workshop with specific hydrogen training. A general recovery operator should be told what the vehicle is before it is loaded.
Likely causes
Start here
- Failed power or earth supply to the module · specialist
- Corroded or loose connector · easy
- Damaged data bus wiring · moderate
Less common
- Blown fuse or failed supply · easy
- Another module holding the bus down · specialist
- Low system voltage · moderate
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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