You undoubtedly know by now that an illuminated Check Engine Light (CEL) means that a sensor for a system in your drivetrain is registering a reading that's out of spec, causing a trouble code to be stored in the powertrain control module (PCM). Since the advent of the OBDII engine management system in the mid-90s, those trouble codes are now standardized across all makes and models and can be accessed with a generic code reader.
The good thing about the OBDII system is that a trouble code takes a good deal of guesswork out of troubleshooting, giving a tech a head start on narrowing down the problem. It's often not as simple as just identifying a problem and replacing parts, though. Sometimes the same problem might result in a cascade of trouble codes, and there's a certain amount of deduction and reading between the lines involved in proper diagnosis and repair.
P0562 (System Voltage Low) — What It Means
Your vehicle's charging system should supply a voltage of 14.1 to 14.7 volts to the battery, when idling with the headlights off. A low voltage supply to the battery and the rest of the electrical system can result in all sorts of erratic performance and other problems. A P0562 code stored in the PCM means that the system voltage is dipping below 10 volts for 60 seconds at a time or more when the engine is running.
- Battery runs down quickly
- Illuminated check engine light
- Battery light on, or charging system amperage reads low on dash gauge
- Misfires, lack of power, dies at stoplights and requires a jump
- Poor fuel economy
- Poor shifting
What Happens If I Ignore It?
Chances are you won't be able to ignore a P0562 code for long. If the system isn't charging the battery properly, the battery won't stay charged for long without needing a jump — and the entire electrical system will try to run on the substandard charge from the battery. In other words, your vehicle will probably be undrivable soon.
In most cases, the P0562 code is going to result from a failing alternator. Other causes can include a bad positive battery cable, bad wiring or connection at the alternator, bad voltage regulator (on vehicles that still have a separate regulator), failing PCM or a dead-short parasitic battery drain. These are all pretty rare instances, though—this code is most often caused by a bad alternator.
Just so you can confirm this diagnosis, the signs of a failing alternator are pretty clear-cut; you can find out more here. The good news is that on many vehicles, replacing the alternator is a pretty simple matter and can be done in a couple of hours with some basic tools. Did we mention that alternator testing is also one of the free services available at your local Advance Auto Parts store?
Let us know in the comments if this is a trouble code you've come across before.