What are the common causes of P063C?

A short to ground in the generator voltage sense wire. Corrosion at the sense connector. A failed alternator. A weak battery or low charging voltage. A faulty ECM sense input.

Check the battery and charging voltage. Inspect the voltage sense wire for a short to ground. Compare the sense reading to battery voltage on a scan tool. Test the alternator output against spec. Repair the short if it is on the sense wire. Clear the code and retest.

P063C

Generator Voltage Sense Circuit A Low

System: Computer output circuits (P code)
Lamp: Check Engine Light
Category: Powertrain - Computer and Auxiliary Controls

What it means

P063C means Generator Voltage Sense Circuit A Low.

Check these first

A short to ground in the generator voltage sense wire
Corrosion at the sense connector
A failed alternator
A weak battery or low charging voltage
A faulty ECM sense input

What to do next

Check the battery and charging voltage
Inspect the voltage sense wire for a short to ground
Compare the sense reading to battery voltage on a scan tool
Test the alternator output against spec
Repair the short if it is on the sense wire
Clear the code and retest

Look up another code

Code or symptom

Enter a full code or a symptom. Press / to search. How to read a code

Type a code above, or start from a symptom or a common code.

Updated

Generic SAE J2012 definition. Last updated 2026-10-10.