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P0561 is a diagnostic trouble code (DTC) for "System Voltage Unstable". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.
If the PCM detects an abnormal voltage reading from the battery, the charging system, or the starting system, it will store the P0561 code.
Even when a vehicle is off, the battery supplies electricity to the ECM, which uses that power to store code histories, fuel trim values, and various other data. If the battery voltage falls below a specific level, the ECM assumes that there is a fault in the power supply circuit, and will alert the PCM to store the P0561 code.
The P0561 code is most often caused by a dead or weakened battery. It may also be due to a defective battery, or one of the following causes:
Common symptoms of the P0561 code may include improper shifting, a decrease in fuel efficiency, engine stalling when idling, slow starting, and the illumination of the Check Engine Light. Low battery power may result in interior lights or other electrical components that don’t function properly.
In order to properly diagnose the root cause of the P0561 code, a mechanic should first perform a visual inspection of the wiring, connectors, and battery cables, and replace or repair any that are faulty. After clearing the code, the mechanic should perform a retest of the system, to ensure that this simple repair did or did not solve the issue. If the mechanic successfully recreates the failure, and the code is stored in the PCM again, they may move on to other repairs.
The most common mistake when diagnosing the P0561 code is a hyper-focus on the battery and starter, when the alternator is often a common problem with this code. It’s important to check if the alternator is properly charging, and that the vehicle’s charging system is operating correctly.
It is also important to be sure that the P0561 code is cleared from the PCM after every repair is performed, and the system is retested. With each clearance and retest, the mechanic will be able to get closer to the true cause of the problem.
If the P0561 code is stored in the PCM, it represents a potentially very serious issue that should be addressed as soon as possible. If the charging system, starter, and/or battery are not working properly, it is unlikely that the vehicle will be operational for very long. As soon as this code is detected, the issue should be diagnosed and repaired.
Repairs that can be performed to fix the P0561 code include:
YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.