P2671: Actuator Supply Voltage B Circuit High
What to do
Expect warning lights and probably reduced power. It is safe enough to drive gently to a workshop, but do not leave it for weeks — parts on this circuit may be powered when they should be resting, and some of them do not tolerate that indefinitely.
Ask for one quick check before anything else: the charging system voltage. An alternator or regulator pushing the whole vehicle's voltage too high puts every supply out of range at once and produces exactly this. It takes a couple of minutes at the battery and rules out a whole investigation.
Otherwise this is usually a chafed loom letting two circuits touch, or a relay whose contacts have welded closed so the supply never switches off. As with the rest of this family, do not replace the parts named by the other codes — they are reporting a supply problem, not their own.
What this code means
The second actuator supply rail reads above its valid range — a short to a higher supply, or a rail that is live when the module commanded it off.
The rail's function and the confusing pattern of codes it produces are described at P2669.
A rail that is high when it should be off is the reading with a consequence beyond this code, and it is worth understanding. The module switches these rails deliberately: actuators are powered down when they should be idle, both to save current and so the module can test the circuit. A rail stuck live leaves solenoids energised when nothing intends them to be — a valve held open, a heater left on, a motor driven against its stop — and those are conditions the parts were not designed to hold indefinitely.
The commonest mechanism is the same one that causes a great many high-circuit faults on a vehicle: a chafed loom putting two circuits together. Where a bundle rubs through against a bracket, the exposed conductors are neighbours in the same bundle, so a supply wire finds a signal wire rather than finding earth. That is why a high-circuit code often arrives with faults on entirely unrelated circuits that happen to run in the same loom.
A welded relay contact is the other route, and it produces the cleaner version — the rail simply never turns off.
Overcharging is worth ruling out before anything is dismantled. A charging system pushing the whole vehicle's supply too high puts every rail out of range at once, and that is a five-minute measurement at the battery rather than a wiring investigation.
Likely causes
Start here
- Wiring shorted to voltage · moderate
- Damaged wiring harness · moderate
- Faulty module power relay · moderate
Less common
- Charging system overvoltage · moderate
- Faulty engine control module · specialist
Symptoms
Components involved
Information, not instruction
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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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