P0B35: High Voltage Service Disconnect Circuit Low
Do not keep driving
As P0B33. The plug itself may be perfectly fine here — it is the wiring that reports on it that has failed — but the car has no way to know that, and refusing to power up is the correct response rather than an overreaction.
What this code means
The service disconnect's monitoring circuit is reading below its valid range — a short to earth, or a signal wire that has lost its supply.
This is a fault in the monitoring, not necessarily in the disconnect: the plug may be perfectly seated while the circuit reporting on it is damaged. The car cannot tell the difference and will not energise either way, which is the conservative answer and the right one.
What the device is, and the rule about never bypassing it, are at P0B33.
Likely causes
Start here
- Wiring shorted to ground · specialist
- Corroded or loose connector · specialist
Less common
- Damaged wiring harness · specialist
- Water ingress into a high voltage connector · 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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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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