OBD-II code · Powertrain (generic)
P063B Generator Voltage Sense Circuit A Range or Performance
Same as P063A with the sense voltage in plausible range yet not matching the alternator output - high contact resistance or wrong calibration.
Is it safe to drive with P063B?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyContact resistance high
- Less likelyPack cell imbalance approaching service threshold
- Less likelyGround point with elevated resistance
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
- 0.5–1.8 h
- Emissions test
- Usually unaffected
- Parts involved
- Alternator Voltage Sense A
Related codes
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.