P0563
System Voltage High.
- Generic
- Powertrain
- Generic code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 5
- AreaVehicle speed, idle control and auxiliary inputs
- 63
- FaultThe specific fault in that area
What it means
P0563 means the engine control unit has seen the system voltage rise above the upper limit it expects while the engine is running or the ignition is on. This is normally caused by the charging system overcharging, but it can also be a wiring or sensing fault. The exact threshold and the way voltage is measured vary between vehicles.
Symptoms
- Battery or charging warning light on the dashboard
- Engine management light illuminated
- Headlights, interior lights or dash illumination unusually bright or flickering
- Battery overheating, swelling or a smell of sulphur or rotten eggs
- Erratic gauges, warning messages or electrical gremlins
- Possible stop-start or other systems disabled, depending on the model
Possible causes
- Faulty alternator voltage regulator causing overcharginglikely
- Poor or corroded earth connection or loose battery terminals giving false or unstable voltage readingspossible
- Faulty or failing battery, such as an internal short or damaged cell, causing abnormal charging behaviourpossible
- Wiring or connector fault in the alternator control or feedback circuit, on vehicles where the control unit commands the alternatorpossible
- Fault in the engine control unit or the battery management system, or its sensorrare
- Incorrect or aftermarket charging components or a jump-start or charger fault that left voltage abnormalrare
How to diagnose
- Read all stored codes and freeze frame data, noting engine speed, load and voltage when the code set, and check for other charging or battery codes
- Visually inspect the battery terminals, earth straps, alternator wiring and connectors for corrosion, looseness or damage
- Measure battery voltage with the engine off, then at idle and at raised engine speed with loads on and off; a healthy system is normally within the manufacturer's specified range, so check the figure for the vehicle
- Compare the measured voltage with the live data voltage reported by the control unit to spot a sensing or wiring fault
- Check voltage drop on the main positive and earth cables between battery, alternator and body
- Test the battery condition and state of health with a suitable load or conductance test
- On vehicles with a smart or controlled alternator, check the control signal and wiring using the manufacturer's procedure, as this varies by model and engine
- Clear the code and road test, then recheck that voltage stays in range and the code does not return
How to fix
- Replace the alternator or its regulator if it is overcharging
- Clean and tighten battery terminals and repair or replace faulty earth connections
- Replace the battery if it is defective, and make sure any new battery is registered or coded where the vehicle requires it
- Repair damaged wiring or connectors in the charging and alternator control circuit
- Update or repair the control unit or battery management system only if testing confirms it is faulty, or a manufacturer update is known to address the cause
Can I keep driving?
Medium severity
Short, careful driving to a workshop is usually acceptable, but sustained overcharging can damage the battery and electronics, so have it checked soon. Stop driving if the battery is hot, swollen or smells strongly, or if warning lights and electrical systems behave erratically.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.