P0563 System Voltage High

The definition

P0563: System Voltage High.

P0563 is a powertrain code (the engine or gearbox), defined by the SAE standard - it means the same thing on any make of car, and any generic OBD-II reader will decode it.

What to check first

Cheapest and fastest checks first:

1. Read the freeze-frame data stored with the fault - engine speed, load and temperature at the moment it logged tell you whether this happens cold, hot or under load.
2. Check the connector at the part for corrosion, and that it is fully seated.
3. Clear the code and see whether it returns, and under what conditions.

What actually causes this on a VAG

Here the ECU has seen supply voltage above the window it expects. Sometimes that's a genuine overcharge, and sometimes it's a one-off logged during a jump start or while a mains charger was connected. On many modern VAGs the alternator isn't a simple self-regulating unit - the engine ECU asks it for a particular output - so a control or wiring problem can leave charging outside the normal range. A measurement decides which of those you've got, and sustained overcharging is worth acting on quickly rather than living with, because it cooks batteries and can damage electronics elsewhere in the car.

Most likely causes, in order

1. Recent jump start, booster pack or charger. If the code appeared around a jump start or a charge, take a voltage reading at the battery with the engine running before you do anything else. If that reading is normal, clear the code and see whether it comes back over the next few days of normal driving - a single stored event with normal measured voltage afterwards isn't a fault to spend money on. Don't dismiss it on the story alone, though: only the measurement tells you whether it's still overcharging now.
2. Alternator regulator failing. The regulator is what holds output in check, and when it fails output can run high. Measure at the battery with the engine running and warm, at idle and at raised revs, and watch whether the voltage climbs and stays up there.
3. Poor connections or earths in the charging wiring. A corroded alternator plug, a poor earth, or a heat-damaged main output connection can leave the regulator working from bad information. Inspect the alternator connector, the main output stud and the fuse/junction block on the battery for corrosion or heat damage.
4. Battery management or monitoring sensor fault. On cars with managed charging, a faulty battery monitoring sensor or the wrong battery details coded in can produce an inappropriate charging target. Check what else is stored across the modules before blaming the alternator.

Worth knowing: Get an actual voltage reading at the battery with the engine running before spending anything. If it's in the normal range and the car has recently been jump-started or charged, this is very likely a stored one-off rather than a failing alternator. If it's genuinely sitting high, don't just clear it and carry on - that's the version of this fault that ruins batteries and electronics.

Common questions

What does P0563 mean?

P0563 means System Voltage High. It is logged when the ECU sees this circuit outside its expected operating window.

Can I drive with P0563?

The engine light will stay on and the car may run in a reduced-power mode. Read the freeze-frame data to see the conditions the fault was logged under.

Related reading

• Battery Keeps Going Flat on a VW or Audi: Finding the Cause
• VW or Audi will not start: working out which problem you have
• Several warning lights on at once: usually one cause, not many
• Why the same fault code has completely different causes