What are the common causes of P063D?

A short to voltage on the generator voltage sense wire. Corrosion or chafing at the sense connector. A failed alternator overcharging. A weak ground at the generator. A faulty ECM sense input.

Check the charging voltage for overcharge. Inspect the voltage sense wire for a short to voltage. Check the generator ground and connectors. Test the alternator output against spec. Repair the short if the sense wire reads high. Clear the code and retest.

P063D

Generator Voltage Sense Circuit A High

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

What it means

P063D means Generator Voltage Sense Circuit A High.

Check these first

A short to voltage on the generator voltage sense wire
Corrosion or chafing at the sense connector
A failed alternator overcharging
A weak ground at the generator
A faulty ECM sense input

What to do next

Check the charging voltage for overcharge
Inspect the voltage sense wire for a short to voltage
Check the generator ground and connectors
Test the alternator output against spec
Repair the short if the sense wire reads high
Clear the code and retest

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Updated

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