P0563: System Voltage High
The engine control unit measured a supply voltage that is too high.
High risk
Overcharging can damage the battery and electronics. Have it checked soon.
Short answer · Can I keep driving with P0563?
Short trips only. Overcharging can damage the battery and electronics. Have the alternator regulator checked soon.
What does P0563 mean?
Code P0563 means the supply voltage is above its maximum, usually because the alternator voltage regulator is not limiting the charge.
Overcharging can boil the battery and damage bulbs and electronic modules.
What the car does when the code is set
The battery warning or check engine light may come on, together with other warnings. Electrical systems may switch off non-essential loads, the start-stop function may stop working and the engine may stall or not restart.
How the system works
With the engine off, the battery supplies all electrical loads. Once the engine runs, the alternator takes over and recharges the battery, holding system voltage at roughly 13.5–14.8 volts depending on temperature and battery management. Control units need a stable supply: too little voltage can make them reset or misread sensors, too much can damage them. The engine control unit measures its supply voltage continuously and stores a code if it stays outside the allowed window for longer than a set time.
Common symptoms
Possible causes
Listed without ranking. The cause on your car depends on make, engine and mileage — see the maker notes below.
- Weak or failing batteryThe battery cannot keep the voltage up.
- Alternator not charging properlyA worn regulator, brushes or slipping belt.
- Poor connectionsLoose or corroded battery terminals and ground straps.
- Wiring fault to the control unitVoltage drop in the supply circuit.
How it is diagnosed
- Measure battery voltageEngine off: about 12.6 V when fully charged. Engine running: usually about 13.5–14.8 V.
- Check terminals and groundsClean and tighten battery terminals and engine and body ground straps.
- Test the batteryA load or conductance test shows whether the battery can still deliver current.
- Test the alternatorCheck charging voltage with lights and blower on. Check the belt condition and tension.
Questions about P0563
Can a battery charger set P0563?
Yes. Charging the battery with a charger while the engine runs or a faulty charger can raise the voltage and set it.
What voltage is too high?
Most systems set a code when the voltage stays above about 16 volts, but the exact limit depends on the manufacturer.
Why do several warning lights come on together?
Low voltage disturbs many control units at once, so several unrelated warnings can appear together. Fixing the supply usually clears them.
Can a dash camera or other accessory cause this?
Accessories that drain the battery while parked can weaken it and set low-voltage codes.