System Voltage High
In short
P0563 means the Engine Control Module (ECM) has detected battery/system voltage that is higher than the expected operating range, usually around 16 volts or more. The most common real-world cause is a faulty alternator voltage regulator that is overcharging the battery, though wiring and connection problems can also trigger it. It is a charging-system code, not an engine misfire code, and overcharging can damage the battery and electronics if left unaddressed.
Is it safe to drive with P0563?
In most cases the vehicle is drivable for short distances, but sustained overcharging can boil the battery, damage sensitive electronics, and shorten component life. If you see the battery/charging warning light, smell rotten eggs (sulfur) from the battery, or notice flickering lights, limit driving and have it checked soon. Do not ignore it for weeks.
Symptoms
- Battery, charging, or check engine light illuminated on the dash
- Headlights and dash lights appear unusually bright or flicker
- Burning or rotten-egg (sulfur) smell from an overcharged battery
- Battery case appears swollen or you notice corrosion and electrolyte residue
- Premature failure of bulbs, fuses, or electronic modules
- Hard or erratic starting if the battery has been damaged by overcharging
Common causes (most → least likely)
How to diagnose it (before buying parts)
- 1 Scan and record the freeze-frame data, then clear the code and confirm whether it returns to verify it is current and not historical.
- 2 With the engine running, measure battery voltage at the terminals with a multimeter — a healthy system reads roughly 13.5 to 14.7V; readings above about 15-16V confirm overcharging.
- 3 Inspect the battery, alternator, and main ground connections for corrosion, looseness, swelling, or heat damage and clean/tighten as needed.
- 4 Back-probe the alternator sensing/field wiring and check the ground circuit for excessive voltage drop (over ~0.2V) that can fool the regulator.
- 5 If voltage is high with good wiring and grounds, bench-test or load-test the alternator to confirm a failed voltage regulator before replacing parts.
Repair options & cost
By manufacturer
On many GM vehicles the PCM commands the alternator output, so P0563 can stem from charging-control circuit or PCM software issues as well as a failed regulator; check connections and the field circuit carefully.
Ford applications with computer-controlled (smart) charging can set P0563 from corroded grounds or a faulty alternator; verify the voltage-sense wiring before condemning the alternator.
These often regulate charging through the PCM and are sensitive to ground and connector corrosion, which can produce inflated voltage readings and trip this code.
Less common, but P0563 on Toyota typically points to an internally failing alternator/regulator or a weak battery affecting the sensed system voltage.
Frequently asked questions
Can I drive with a P0563 code?
You can usually drive short distances, but sustained overcharging can damage the battery and electronics. Get it diagnosed soon, and stop driving if you smell sulfur, see a swollen battery, or notice flickering lights.
Is P0563 caused by a bad alternator or a bad battery?
It is most often the alternator's voltage regulator overcharging the system, but a failing battery or poor grounds can also cause it. Measuring charging voltage with a multimeter is the fastest way to tell which.
What voltage is too high for P0563?
A normal charging system reads about 13.5 to 14.7 volts at the battery with the engine running. Many vehicles set P0563 when sensed voltage climbs above roughly 16 volts, indicating overcharging.
How much does it cost to fix P0563?
Simple fixes like cleaning a ground connection may cost little to nothing, while alternator replacement commonly runs about 300 to 700 dollars at a shop. Diagnosis first prevents replacing parts you do not need.