What it means
The voltage in sensor power supply A is below 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 A feeds a vehicle-dependent group of sensors from a module-managed rail. P06B1 sets when the rail voltage is lower than the module expects, often because the line is shorted to ground or a poor connection is restricting supply.
Common causes
Most likely first.
- Supply line shorted to ground
- Connector pins corroded - high contact resistance
- Harness chafing through insulation
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, save freeze-frame data, and identify companion faults that could involve sensors sharing supply A.
- Use live data to see which sensors on supply A have missing or abnormal readings and whether the fault appears with particular operating conditions.
- Inspect supply A wiring, module and sensor connectors, and harness routing for chafing, corrosion, moisture, or loose terminals.
- With the wiring diagram, measure supply A as directed by the manufacturer's procedure and check for a short to ground or excessive resistance.
- If the external wiring passes, check module supply output and sensor loads according to the manufacturer's specification.
Common fixes
- Clean and secure a high-resistance connector contact.
- Repair chafed supply A wiring or a short to ground.
- Repair a sensor or branch that is pulling the shared supply low, as identified by testing.
- Repair or replace the module if its supply A output is confirmed faulty.
Can I keep driving?
If the low supply affects engine-control sensors, the vehicle may run poorly, lose power, or stall, so avoid high-speed trips and heavy loads. Stop driving if it becomes difficult to control or repeatedly loses power.
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.