What it means
The voltage in sensor power supply B is above the expected range. This may affect components supplied by that circuit; which ones 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 shared, module-managed rail for a vehicle-dependent set of sensors. P06B5 sets when the rail voltage is higher than expected, which can result from a short to a higher-voltage source or a fault in the module's supply control.
Common causes
Most likely first.
- Supply line shorted to higher voltage
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
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 record freeze-frame data, looking for faults in sensors that may share supply B.
- Check live data for those sensors and see whether multiple readings became abnormal together.
- Inspect supply B wiring and connectors for chafing against a B+ source, moisture, corrosion, or loose terminals.
- Use the wiring diagram and manufacturer's procedure to measure the rail and test for a short to a higher-voltage circuit.
- If wiring and connected components pass, check module supply B output against the manufacturer's specification.
Common fixes
- Secure a loose connector or clean poor terminal contacts.
- Repair supply B wiring that is shorted to a higher-voltage source.
- Replace a failed sensor or branch component if testing shows it is driving the shared rail high.
- Repair or replace the module if its supply B output is confirmed faulty.
Can I keep driving?
Limit driving until the cause is identified, because excessive voltage on supply B can disrupt multiple sensors and affect engine operation. Stop if the vehicle runs erratically, loses power, or develops additional warnings.
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.