P0653Sensor Reference Voltage "B" Circuit High
What it means
The 5 V reference "B" is too high: usually shorted to a higher voltage.
Symptoms
- Several sensor codes at the same time
- Limp mode, possibly no start
- Erratic gauges or throttle
Common causes
- Reference wire open or shorted to voltage
- Connector fault
- ECU fault
What to check first
- Find which sensors share this reference (wiring diagram)
- Unplug them one at a time and watch whether the reference recovers to 5 V
- Inspect the shared wiring and splices
Generic OBD-II meaning. Manufacturer-specific meanings and checks can differ; always check the service information for the car.