OBD-II code · Powertrain (generic)
P06A4 Sensor Reference Voltage D Circuit Low
Same as P0652 on reference rail D. 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 P06A4?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyReference rail 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 Reference Voltage D
Related codes
- P0652Sensor Reference Voltage B Circuit Low
- P0698Sensor Reference Voltage C Circuit Low
- P06D3Sensor Reference Voltage E Circuit Low
- P06D7Sensor Reference Voltage F Circuit Low
- P262DSensor Reference Voltage G Circuit Low
- P06A1Variable A/C Compressor Control Circuit Low
- P06A2Variable A/C Compressor Control Circuit High
- P06A3Sensor Reference Voltage D Circuit Open
- P06A5Sensor Reference Voltage D Circuit High
- P06A6Sensor Reference Voltage A Circuit Range or Performance
- P06A7Sensor Reference Voltage B Circuit Range or Performance
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.