What are the common causes of P063A?

A wiring fault in the generator voltage sense wire. Corrosion at the sense connector. A failed alternator. A faulty ECM sense input. A bad battery connection.

Check the battery connections and charging voltage. Inspect the voltage sense wire and connector. Compare the sense reading to battery voltage on a scan tool. Test the alternator output against spec. Repair the sense circuit if the reading does not match battery voltage. Clear the code and retest.

P063A

Generator Voltage Sense Circuit A

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

What it means

P063A means Generator Voltage Sense Circuit A.

Check these first

A wiring fault in the generator voltage sense wire
Corrosion at the sense connector
A failed alternator
A faulty ECM sense input
A bad battery connection

What to do next

Check the battery connections and charging voltage
Inspect the voltage sense wire and connector
Compare the sense reading to battery voltage on a scan tool
Test the alternator output against spec
Repair the sense circuit if the reading does not match battery voltage
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.