OBD-II code · Powertrain (generic)
P06B4 Sensor Power Supply B Circuit Low
Same as P06B1 on supply rail B. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
Is it safe to drive with P06B4?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelySupply line shorted to ground
- Less likelyConnector pins corroded - high contact resistance
- Less likelyHarness 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
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.5–2 h
- Emissions test
- Likely to fail
- Parts involved
- Sensor Power Supply B
Related codes
- P06B1Sensor Power Supply A Circuit Low
- P06E7Sensor Power Supply C Circuit Low
- P26E0Sensor Power Supply D Circuit Low
- P06B2Sensor Power Supply A Circuit High
- P06B3Sensor Power Supply B Circuit Open
- P06B5Sensor Power Supply B Circuit High
- P06B6Internal Control Module Knock Combustion Vibration Sensor Processor 1 Performance
- P06B7Internal Control Module Knock Combustion Vibration Sensor Processor 2 Performance
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.