U0057: Vehicle Communication Bus D (+) Open
What to do
Expect a group of systems to have stopped working together — and expect the battery to go flat if the car is left standing.
That second part is worth planning around rather than treating as a separate problem. A car goes to sleep by agreement between its computers, and a broken network wire means the message never reaches some of them — so they stay awake indefinitely and drain the battery.
So if the car is going to sit waiting for a repair, disconnect the battery or it will simply flatten itself again, and charging it without fixing the wiring changes nothing.
One broken wire causes all of this — see U0003 for why breaking either wire stops the whole network. Do not let computers be replaced on the strength of the fault list.
When the break is found, ask for the second wire to be inspected along the same stretch. They run twisted together, so whatever damaged one was touching the other.
What this code means
The positive line of vehicle communication bus D is open circuit. See U0003 for what an open does to a differential pair, U0030 for the procedure on a lettered bus, and U0039 for why where the break falls decides what a resistance reading shows.
One point belongs here and it follows U0055.
A network that is broken cannot negotiate sleep either. So an open circuit on a bus frequently produces a flat battery alongside the obvious symptoms — modules on the far side of the break never receive the message that the vehicle is going to sleep, and stay awake indefinitely.
Which is worth expecting rather than treating as a second fault. A vehicle recovered with a flat battery and a bus open circuit has one problem, and charging the battery without repairing the wiring simply repeats the discharge.
And it is a reason to disconnect the battery while the vehicle waits for repair, rather than leaving it to flatten itself again.
Likely causes
Start here
- Damaged data bus wiring · moderate
- Corroded or loose connector · easy
- Damaged wiring harness · moderate
- Failed bus terminating resistor · specialist
Less common
- Water ingress into connector · moderate
- Poor wiring splice in an aftermarket installation · 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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