What it means
The sensor power supply B circuit is open, interrupting power to components supplied by that circuit. Which sensors are affected depends on the vehicle.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Sensor power supply B is a module-managed rail that powers a vehicle-dependent group of sensors. P06B3 sets when the module detects an open in supply B, so sensors on that rail may lose power and report related faults.
Common causes
Most likely first.
- Open in supply rail
- Pin pushed back out of connector body
- Cracked solder joint inside the module or sensor
Symptoms
- Check engine light on
- Possible limp mode or no-start
- Multiple follow-up faults across modules
- Reset/relearn may be needed after repair
How to diagnose it
- Scan all modules and save freeze-frame data, looking for sensor faults that appeared together and may share supply B.
- Check live data for the likely supply B sensors and identify readings that are missing or implausible at the same time.
- Inspect supply B wiring and connectors at the module and affected sensors for loose plugs, pushed-back pins, corrosion, or damage.
- Follow the wiring diagram to test supply B continuity and locate an open between the module and affected branches.
- If the external rail is intact, check the module output and internal connections under the manufacturer's procedure.
Common fixes
- Reconnect a loose plug or correctly seat a pushed-back terminal.
- Repair a broken supply B wire or damaged connector.
- Repair an internal connection in a serviceable module or sensor assembly if testing identifies it.
- Replace the module or component only after confirming its supply B output or internal connection has failed.
Can I keep driving?
If the affected sensors are needed for engine control, an open supply B rail can cause poor running, reduced power, or a no-start. Avoid a trip if those symptoms occur, and stop if the vehicle stalls or becomes unreliable.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.