U0050: Vehicle Communication Bus C (+) High
What to do
This is one of the faults that can damage things rather than just stopping them, and on this network the things are expensive.
Full battery voltage has got onto a network wire, and every unit on that network is connected to it — which here usually means the stereo, the amplifier and the navigation unit. Many of those are coded to your car, so a damaged one cannot simply be replaced with a second-hand part.
So be prepared for a repair in two stages, and do not keep using the system until the short has been found — the voltage is still there, still stressing whatever survived it.
The cause is nearly always an added power feed. A stereo, amplifier, subwoofer, tracker or dashcam installation, where a live wire was tapped next to the network wires or a self-stripping connector was clipped onto the wrong one in a bundle.
Say what has been fitted, including by a previous owner, and ask for it to be unplugged and the car re-tested first. That is quicker than any measurement.
What this code means
The positive line of vehicle communication bus C is being held high. See U0005 for the module-damage warning — battery voltage on a bus wire can destroy the transceiver in every module on that network, so the repair may have two stages.
On an entertainment network that warning has a particular cost worth knowing, because the modules concerned are expensive and often tied to the vehicle.
A head unit, an amplifier and a navigation module are among the pricier units on a vehicle, and many of them are coded to the vehicle or to its immobiliser — so a damaged one is not simply replaced with a used part. See U0184 and U0334.
Which makes the two-stage warning more than a caution about the bill. It is a reason to find the short before running the system again, because voltage left on the pair continues to stress whatever survived the first exposure.
The cause is nearly always an added power feed — a live tapped beside the bus pair, a self-stripping connector on the wrong wire in a bundle, or a screw through a loom while mounting an amplifier or a bracket.
Likely causes
Start here
- Poor wiring splice in an aftermarket installation · moderate
- Wiring shorted to voltage · moderate
- Aftermarket head unit fitted in place of the original · moderate
- Damaged data bus wiring · moderate
Less common
- Faulty aftermarket alarm or immobiliser installation · moderate
- Damaged wiring harness · 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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