OBD-II · Engine and powertrain (P)
P0563
System voltage high
What it means
The ECU's supply voltage has risen above its maximum, usually from overcharging.
Symptoms
- battery warning light
- bulbs blowing or very bright lights
- battery smelling or hot
- engine warning light
Likely causes, most likely first
| No. | Cause |
|---|---|
| 01 | faulty alternator voltage regulator |
| 02 | poor battery earth or sense connection |
| 03 | faulty battery sensor |
| 04 | jump-starter or charger connected while running |
What to check, step by step
- 01If the battery is abnormally hot, swollen, leaking or emitting a strong sulphurous smell, stop safely and switch off; avoid sparks and have it assessed before running, charging or load-testing it.
- 02Measure battery voltage with the engine off (about 12.4-12.7 V when charged) and running; note that smart charging on modern cars varies the voltage deliberately
- 03Test the battery with a conductance or load tester; start-stop cars need the correct AGM or EFB type
- 04Clean and tighten the battery terminals and the main engine and body earth straps
- 05Check the alternator belt, tensioner and freewheel pulley
- 06Check the alternator control wiring (single wire or LIN bus on many modern cars) and the battery sensor on the negative terminal