P063A
Generator Voltage Sense Circuit A
A general circuit fault is detected on the alternator voltage sense line A - the line over which the regulator measures battery-side voltage to set charging output.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
Symptoms
- Check engine light on
- Possible limp mode or no-start
- Multiple follow-up faults across modules
- Reset/relearn may be needed after repair
Common causes
Ordered by how often each turns out to be the cause.
- Open in sense lineCommon
- Pack cell imbalance approaching service thresholdLess likely
- Ground point with elevated resistanceLess likely
Parts involved
- Alternator Voltage Sense A
P063A is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.