U0061: Vehicle Communication Bus D (-) Low
What to do
As at U0058: if the car drives perfectly and keeps going flat when it stands, this is very likely why, and it is one problem rather than two.
Ask for the drain to be measured while the car is parked and settling rather than during a road test — the fault is often absent while the engine is running, which is exactly why it gets missed.
And one more specific request that costs nothing: ask them to read the conditions stored with the fault, not just the fault.
Most computers record what was happening at the moment they logged a problem — the battery voltage, how long since the car woke up, sometimes the temperature. On a fault that comes and goes, that record is often the only evidence there is.
A fault always logged at low battery voltage points at the battery or charging rather than the wiring. One logged just after the car goes to sleep points somewhere else again.
All of that is destroyed the moment somebody clears the codes — so ask for it to be read before anything is reset.
What this code means
The negative line of vehicle communication bus D is being held low. Everything at U0058 applies — including that this fault reliably flattens a battery, that it often clears while the vehicle is running, and that the measurement therefore belongs to a parked vehicle rather than a road test.
One addition specific to a fault that comes and goes with standing: the freeze frame.
Most modules record conditions at the moment a fault is stored — voltage, time since the network last woke, sometimes ambient temperature. On an intermittent bus fault that record is often the only evidence there is, because the fault is absent by the time anybody looks.
So a specific and reasonable request: read the stored conditions rather than only the code. A fault consistently stored at low system voltage points at the battery or the charging system rather than the wiring — U0100's list includes low voltage for exactly this reason — while one stored shortly after sleep points at the transition case at U0056, and one stored at a consistent temperature points at damp or thermal movement.
None of that requires an extra visit, and all of it is thrown away when a code is read and cleared.
Likely causes
Start here
- Water ingress into connector · moderate
- Wiring shorted to ground · moderate
- Another module holding the bus down · specialist
- Low system voltage · moderate
Less common
- Damaged data bus wiring · moderate
- Intermittent wiring fault · 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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Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
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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