P0563: The electrical system voltage is running too high
System Voltage High
System voltage is too high, usually a charging system fault, and it can damage the battery and electronics. Get it checked within a day or two. If you smell burning or see a battery warning, stop driving.
Stop driving and get help if
- The check engine light is flashing
- The temperature gauge runs high, or you see steam (overheating)
- The car loses power, hesitates badly or stalls
- You smell burning or see smoke
- A brake warning light comes on, or the brakes feel different
Pull over as soon as you can, turn the engine off, and call a tow or roadside help.
What it means
P0563 means the PCM detected charging system voltage above a safe threshold, typically above 16 volts. Normal charging is 13.5 to 14.8 volts. When voltage exceeds this, the alternator is overcharging and can boil the battery, damage its cells, and harm voltage-sensitive modules. A failed voltage regulator inside the alternator is the most common cause. On most modern vehicles, the regulator is built into the alternator. On some older vehicles it is a separate external part, which is a cheap fix if that is what is at fault.
Common causes
- Failed voltage regulatorMost common cause. On most modern cars it is built into the alternator and requires alternator replacement.
- Faulty alternator with internal overcharge conditionThe alternator itself is commanding full output and not backing off.
- PCM voltage reference or sensor errorRare. The PCM could be reading voltage incorrectly. Verify with a separate multimeter before assuming overcharge.
What the fix could involve
From the cheaper fix to the bigger one. Prices depend on your car, your area and the shop, so ask for a written quote that names the part and the labor before you approve it.
- Voltage regulator (external, older vehicles)
- Alternator replacement
Symptoms
- Check engine light on
- Battery warning light may be on
- Burning smell from the battery in severe cases
- Bulbs burning out frequently
- Electronics behaving erratically
What to do next
Verify the overcharge with a multimeter at the battery terminals while the engine runs. If you see over 15 volts, the alternator or regulator is at fault. Compare to the PCM reading; if they agree, the alternator is the problem. Do not let the car sit running with an overcharging alternator; it will damage the battery and potentially other electronics.
Lewis reads P0563 alongside any related charging codes, so you can see whether other computers are also reporting voltage problems. Get Lewis on the App Store or Google Play.
Related codes
FAQ
- Can high voltage ruin my battery?
- Yes. Sustained voltage over 15 volts can boil the electrolyte in a lead-acid battery, permanently damaging it. Check the battery after fixing the alternator.
- Is this an immediate breakdown risk?
- Not immediately, but the battery can fail quickly from overcharging, which then leaves you stranded. Get it checked within a day or two.
- My multimeter shows normal voltage but the code is still there. What now?
- The fault may have been intermittent. If the PCM reading matches your multimeter and both show normal, clear the code and monitor it. If it returns, have the alternator load-tested.
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