U0068: Vehicle Communication Bus E (+) High
What to do
Unlike the other intermittent faults on this network, this one should not be left running while you gather evidence.
Full battery voltage is getting onto a network wire that every computer on that network is connected to — see U0005.
And if it comes and goes, that is worse rather than better. Every time it happens, the damage is applied again — so a fault that has been intermittent for months has done it hundreds of times.
So do not drive it while somebody waits for the fault to reappear.
The cause is nearly always something fitted after the car was built — a tracker, dashcam, alarm, stereo, light bar or tow bar. Unplugging it is both the test and the protection in the meantime, which makes it the right first move rather than a shortcut.
Say what has been fitted, including by a previous owner. And be prepared for the repair to have two stages — the wiring fault, and then whatever was damaged.
What this code means
The positive line of vehicle communication bus E 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.
One thing follows from U0064 and it is worth stating because it changes the urgency of an intermittent case.
An intermittent short to earth is inconvenient. An intermittent short to power is cumulative. Every occurrence applies the damaging condition again, and a fault that has been coming and going for months has done so hundreds of times.
So where the two other faults on this network reward patience — waiting for the fault to be present, gathering observations — this one does not. A vehicle with an intermittent short to power should have the network isolated or the accessory removed rather than driven while evidence is collected.
And the cause is nearly always something added, so unplugging it is both the diagnosis and the interim protection — which makes it the right first move rather than a shortcut.
Likely causes
Start here
- Poor wiring splice in an aftermarket installation · moderate
- Wiring shorted to voltage · moderate
- Faulty aftermarket alarm or immobiliser installation · moderate
- Intermittent wiring fault · moderate
Less common
- Damaged data bus wiring · 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
Be the first to write this up
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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