P063C
Generator Voltage Sense Circuit A Low
Charging system
Generic OBD-II
High
What it means
P063C means the PCM read a low voltage on the generator (alternator) voltage-sense circuit — the feedback it uses to regulate charging. A low or lost sense signal can lead to undercharging, so you may see a battery/charging warning, dim lights, and eventually a discharged battery and stalling. Check the sense wiring and connector, then test the battery and alternator output.
High
Can I keep driving? Limited — the charging system may be undercharging, which can drain the battery and eventually stall the car. Fix promptly.
Common symptoms
What you'll notice
- Battery or charging warning light on
- Check-engine light on
- Dim or flickering headlights and dash lights
- Weak battery, hard starting, or stalling if it discharges
Common causes
Most likely first
- Faulty alternator/generatorLikely
- Open or short-to-ground in the voltage-sense wireCommon
- Corroded or loose connector in the sense circuitCommon
- Weak or failing battery affecting readingsLess often
- PCM/regulator control fault (less common)Less often
How to diagnose & fix
Work through it in order
- Load-test the battery and measure charging output at idle and with loads on.
- Inspect the generator voltage-sense wire and connector for corrosion, opens, or a short-to-ground.
- Check the main charging cables and grounds for voltage drop.
- Replace the alternator if output is low with good wiring. Clear and re-test charging voltage.
FAQ
Quick answers
Is it safe to drive with P063C?+
Only for short distances. If the charging system is undercharging, the battery will slowly drain and the car can stall. Get the charging system tested soon.
Can I just clear P063C?+
It returns while the sense circuit or charging fault remains. Test the battery and alternator, and repair the wiring first.
Related codes
Often seen with P063C
Read & clear P063C yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX