P06B4 code meaning
Sensor Power Supply B Circuit Low
Powertrain system Generic code P06xx codes Check engine light
What P06B4 means
Despite the similar name, 'sensor power supply' is not the 5 V sensor reference (P0641 ff). It is documented in GM hybrid drive motor control modules: a 15 V supply that excites the motor position sensor (resolver) and powers the gate drivers of the inverter transistors, kept separate from the 5 V reference and the 12 V supply. In GM's 2008 Two-Mode hybrid, A and B are the two motor control modules. P06B4 means supply B, in the second motor control module, is too low: GM's 2008 Two-Mode hybrid flags below 12.0 V for 365 ms after two trips. Blown fuses, shorts in supplied components or an internal fault are typical. Mitsubishi's 2022 Outlander lists it as a sub-code.
P06B4 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor1 to 4 hours
- Clears after repairAfter a drive cycle
Symptoms of P06B4
- Check engine or hybrid warning light
- Electric drive or hybrid mode limited or disabled
- Further motor position or inverter codes
Common causes of P06B4
- Most likelyBlown supply fuse
- PossibleSupplied component or wire shorted to ground
- PossibleInternal supply circuit faulty
- Less likelyLow 12 V system voltage
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Sensor power supply circuitDrive motor control moduleResolver
What each part of P06B4 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 6 | Area: computer (engine control module) and output circuits. |
| B4 | The exact fault in that area. |
What to do next
- Note P06B4 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P06B4
What does P06B4 mean?
P06B4 means "Sensor Power Supply B Circuit Low". Despite the similar name, 'sensor power supply' is not the 5 V sensor reference (P0641 ff). It is a generic code, so it means the same on every make.
Is it safe to drive with P06B4?
Drive gently and only to a workshop. With P06B4 the car can go into limp mode (reduced power) to protect itself.
Will P06B4 fail an emissions test?
Yes, it can. P06B4 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P06B4 to fix?
Difficulty: hard. A typical repair takes 1 to 4 hours of work. This is a job for a workshop.
Will P06B4 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.