U0295: Lost Communication With AC/AC Converter Control Module
What to do
The vehicle drives normally in most cases; what has stopped depends on what this converter serves on your particular vehicle.
This is uncommon equipment, and your vehicle's own documentation is the right reference — on a converted or commercial vehicle it may have been fitted by the body builder rather than the manufacturer, in which case they are the people to ask.
As with every code of this kind, it says the module has stopped being heard, not that it has failed. Power, earth, connector and network wiring are all commoner and cheaper explanations, and they should be checked before the module is replaced.
If this relates to charging equipment or anything handling mains-type power, do not investigate it yourself. Those voltages can kill, and it needs somebody properly equipped.
What this code means
The AC to AC converter control module has stopped being heard from. See U0200 for the block's framing.
This is uncommon equipment and the honest description is a general one. An AC to AC converter changes alternating current of one voltage or frequency into another, and on a vehicle that arises where mains-type power is being handled — most often in charging equipment, in auxiliary power systems on commercial and specialist vehicles, or in on-board supplies serving equipment that needs a particular voltage or frequency.
What the vehicle in front of you actually uses it for is a question for its own documentation, and saying so is more useful than a confident description that may not apply.
What can be said with confidence is what the code means and what to do about it, which is the block's standard reasoning and genuinely the right approach. The code says the module has stopped being heard on the network. It does not say the module has failed — its power supply, its earth, its connector and the network wiring are all commoner explanations, exactly as at U0100.
Two practical points are worth adding.
If the vehicle carries auxiliary or converted power equipment, the U0259 reasoning applies: that equipment and its module may have been fitted by a converter rather than the vehicle manufacturer, and their documentation and support are the right starting point.
And if the equipment involved is charging equipment, treat it as high-voltage. Anything that handles mains-side power on a vehicle is capable of delivering a lethal shock, and the corpus's usual encouragement to inspect connectors does not extend to it. Leave it to somebody equipped for the work.
Likely causes
Start here
- Corroded or loose connector · easy
- Failed power or earth supply to the module · moderate
- Damaged data bus wiring · moderate
Less common
- Blown fuse or failed supply · easy
- Water ingress into module · 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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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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