P0563 code definition
This code is also known as System Voltage High, or in some makes of vehicles, Battery System High.
What the P0563 code means
The ECM (engine control module) receives power from the battery even when the vehicle is turned off. This permits data storage and other essential functions.
A vehicle will store this fault code when the ECM detects a voltage reading which is out of range from what is expected. The ECM assumes a power supply circuit fault and automatically triggers P0563 and often the Service Engine Soon lamp. This voltage variation could originate from the battery itself, the alternator, or other components in the starting system or the charging system.
What causes the P0563 code?
Problems that could cause the system voltage to be out of range include:
- A faulty alternator
- A bad battery
- A bad starter
- A faulty voltage regulator
- Corrosion at the battery terminals
- Unusual battery drain
- A short or open in the battery cables or wiring
- A faulty PCM (rarely)
What are the symptoms of the P0563 code?
The battery light may come on, the engine could stall while idling, automatic transmission may not function properly, the Check Engine Light may illuminate, and if left un-repaired, fuel efficiency could be affected.
How does a mechanic diagnose the P0563 code?
A qualified technician may follow these steps to identify the source of the code:
Use an OBD-II scanner to gather freeze frame and other data from the vehicle’s computer, followed by resetting the code to see if it returns
Visually inspect all wiring, cables, and connectors related to the battery, and the starting and charging systems
Perform a load test on the battery
Assess battery voltage readings using a starting/charging system tester
Test the starter current draw using an amp probe
Test the alternator circuits with an ohmmeter
Perform a continuity test on the system circuits
Common mistakes when diagnosing the P0563 code
It’s common for people to replace the battery first without determining whether that’s actually the source of the problem. Frequently, the alternator is the issue, so it’s vital that all systems are tested and all wiring and cables checked thoroughly. Some drivers have been told to replace their entire transmission because the vehicle may enter limp mode when storing this code. This is an extremely expensive, usually unnecessary repair in this situation.
How serious is the P0563 code?
This code can impair your vehicle’s ability to be driven, possibly putting it into limp mode or even preventing it from starting at all. Any time there is something wrong with the charging or starting system, you should have the problem assessed and repaired by a qualified technician as soon as possible.
What repairs can fix the P0563 code?
Possible repairs that may need to be performed to fix this fault code include:
- Replacing the battery cables
- Replacing the battery
- Cleaning corrosion from the battery terminals and posts
- Replacing the alternator (the most common source of the malfunction)
- Replacing the starter
- Replacing the PCM (rarely)
Additional comments for consideration regarding the P0563 code
Once the battery or other components have been replaced, it’s critical that all codes be cleared from the vehicle’s computer. If all codes are not erased, the vehicle may still perceive an issue, even with brand new components installed.
Some vehicle makes have a potential problem with transmission fluid leaking onto a terminal near the TCM (transmission control module) which can cause a short in the circuit board. This is a particularly prominent issue in some Mercedes models. Always get a second opinion from a qualified professional before going ahead with a transmission replacement. The problem could lie in the P0563 code rather than the actual transmission.
Need help with a P0563 code?
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