P0563 — System Voltage High

What it means

The supply voltage at the ECU has exceeded the upper limit, on a 12 V system usually above about 16 V, for longer than the calibrated time. The cause is almost always a voltage regulator that no longer limits the alternator output. Overvoltage boils the battery electrolyte, blows bulbs and can destroy control modules, so the code is serious even though the engine still runs normally.

Likely causes (most common first)

1. Faulty alternator voltage regulator stuck at full field current
2. Broken sensing wire between the alternator and the battery or the ECU
3. Poor ground connection at the alternator housing or the engine earth strap
4. Battery with an internal open circuit no longer damping the system
5. Incorrect alternator or regulator fitted, or a 24 V jump start applied
6. ECU or body control module misreading the voltage on its supply pin

Can you drive with it?

Stop driving as soon as it is safe: sustained overvoltage damages the battery, lamps and electronic modules, and can cause a fire.