P0B37: High Voltage Service Disconnect Open
Do not keep driving
The likeliest explanation is that the plug is out or not fully latched after recent work — mention any recent service or repair immediately, because that turns a recovery into a two-minute fix. If this appeared after any collision or impact near the battery, do not investigate it and do not attempt to move the vehicle: keep clear and call for professional recovery. And whatever the circumstances, this circuit must never be bridged or bypassed to make the car drivable.
What this code means
The service disconnect is open. Not a circuit fault — the loop is genuinely broken, and as far as the vehicle is concerned the traction battery is currently split.
This is the one code in the group that is usually not a fault at all. It is the car correctly reporting that its main safety device has been removed or released, and the overwhelmingly likely reason is that somebody did exactly that: the plug is out, or it was refitted without being latched, and the vehicle has been asked to start before the job was finished.
So the sequence to check is short and free. Has anything been done to this vehicle recently — a service, a battery inspection, a coolant repair, bodywork near the pack, a recovery? If so, the disconnect is the first thing to look at, and reseating it correctly resolves the great majority of these.
When the answer is genuinely no, the readings that remain are a latch that has vibrated loose, a corroded contact that has finally stopped making, or collision damage to the pack area. The last of those deserves its own caution: after any impact near the battery, a broken interlock is a reason to keep away from the vehicle rather than to investigate it.
What the disconnect is for, and the rule that it is never bypassed, are at P0B33 — and that rule is at its most tempting and its most dangerous here, because the car is immobile and the loop looks like a simple switch.
Likely causes
Start here
- High voltage service plug not fully seated · specialist
- High voltage cover or connector not latched · specialist
Less common
- Corroded or loose connector · specialist
- Accident damage to high voltage components · specialist
- Damaged wiring harness · specialist
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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