Powertrain, generic · Computer and auxiliary outputs
P063D Generator Voltage Sense Circuit A High
Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo
Some charging systems measure the actual battery or alternator voltage through a separate sense line (regulator terminal S or an input of the module) to compensate voltage drops in the charging cable; without it the system reports a charging fault. No manufacturer document available to us uses P063A–P063D, so these descriptions follow the circuit principle and CARB, under which a charging-system input needs the check engine light only if it affects emissions or other diagnostics. P063D means the sense voltage is above its limit – a short to a higher voltage, overvoltage or a regulator fault.
Likely causes
Sense wire, fuse or connector between battery and alternator or module open or corroded
Alternator or regulator faulty
Contact resistance at battery terminals or grounds
Battery faulty
Symptoms
- Battery warning lamp on
- Charging voltage too high or too low (flat or overcharged battery)
- Flickering lights
- Further voltage codes (P0562/P0563)
Repair estimate
DifficultyMediumWorkshop job
Parts and labour€20–600
Time0.5–2.5 h
Typical range across vehicles; the real cost depends on what the testing finds.
Parts involved
generator voltage sense circuitalternatorbattery
Related codes
References: law.cornell.edu, pmmonline.co.uk, hella.com.