U0296: Lost Communication With AC/DC Converter Control Module A
What to do
The car will drive normally and will not charge from a normal AC charger — so treat the charge you have now as all you are going to get. Get the vehicle home or to a workshop while it still has the range, and do not set off anywhere assuming you can top up.
One thing worth trying before you assume the car is stuck: a rapid DC charger. A rapid charger converts the power inside the charge post and feeds the battery directly, bypassing the part of your car that has failed — so a vehicle that will not charge at home very often charges perfectly at a rapid point. That is frequently the difference between a recovery truck and simply driving it in.
Ask for the 12-volt battery to be tested first. Electric cars still have an ordinary 12-volt battery running their computers, and a weak one stops the car charging while looking like a much bigger fault. It is cheap, it is common, and it gets missed.
Do not investigate the charging system yourself — it handles mains voltages and high-voltage DC, both of which can kill.
What this code means
The first AC to DC converter control module has stopped being heard from. See U0200 for the block's framing.
On a plug-in vehicle, the AC to DC converter is the on-board charger — and that makes this the code that stops the car being refuelled.
The electricity from a domestic socket or a public AC charge point is alternating current. A battery can only be charged with direct current. The conversion has to happen somewhere, and on AC charging it happens on the vehicle: the on-board charger takes mains AC, rectifies and regulates it, and delivers the DC the battery management system asks for. It is also what negotiates with the charge point about how much current may safely be drawn.
So the consequence is specific and serious in a way no other body-network code is: the vehicle drives perfectly and cannot be charged. For an owner, that is a countdown rather than a fault — whatever is in the battery now is all there is, and the practical advice follows directly.
Two things are worth knowing, and the second surprises people.
Plan around the remaining charge immediately. Do not set off on a journey assuming you can top up, and get the vehicle to where it needs to be — home or a workshop — while it still has the range to do so.
Rapid DC charging may still work. A DC rapid charger does its conversion in the charge post and feeds direct current straight to the battery, bypassing the on-board charger entirely. So a vehicle that will not take AC charge at home may charge perfectly at a rapid point — which is worth trying before assuming the car is immobile, and is often the difference between a recovery truck and driving it in.
Before anything expensive, the ordinary causes deserve their turn: the module's supply and earth, its connector, the network wiring, and — as at U0293 — a weak 12-volt battery, which prevents charging on many electric vehicles and is regularly missed.
Likely causes
Start here
- Failed power or earth supply to the module · moderate
- Corroded or loose connector · easy
- Damaged data bus wiring · moderate
- Blown fuse or failed supply · easy
Less common
- Water ingress into module · moderate
- Charging command fault from the control module · specialist
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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