P0562: System Voltage Low
P0562 means a control module measured its own supply voltage below the expected minimum while the engine was running, which usually points to a weak charging system or a bad battery. It is moderately serious: the car may keep running, but if the voltage keeps falling it can stall or fail to restart.
You can drive, but get it checked soon
The code itself does not cause limp mode, but low voltage means the battery may be draining. If the alternator is failing, the car can lose power to its modules and stop running, so get the charging system checked soon and avoid long trips.
What it means
A control module is a small computer that runs a part of the car, such as the engine or brakes. Each module measures the voltage it receives. P0562 is stored when that voltage drops below a set threshold while the engine runs, a time when the alternator (the generator driven by the engine) should be supplying power. The reference gives one example: on GM engine modules, the code sets at 9 volts or less at 400 rpm or more, in 400 of 500 samples, which is about 5 seconds. Other modules, such as GM's brake module, can set P0562 on their own, so you may see it in more than one module. The code does not turn on the check engine light, and it is not an emissions code. Some modules, such as those in the Saab 9-4X, may switch off temporarily when voltage falls below about 9 volts.
Likely causes
- Alternator or regulator delivering too littleVery likely
The alternator and its regulator (the part that controls its output) must keep voltage up while the engine runs, and if they fall short, voltage drops.
- Faulty battery (shorted cell)Very likely
A battery with a shorted cell cannot hold normal voltage and can pull the whole system down.
- Corroded terminals, ground straps or alternator cablePossible
Corrosion or a loose connection adds resistance, so less voltage reaches the modules even if the alternator works.
- High quiescent current or many consumers at idleLess likely
Parts that draw power when the car is off, or heavy electrical loads at idle, can pull voltage below the threshold.
What you may notice
- Battery or charge warning lamp
- Starting problems or dim lights
- Codes stored in several modules
What to check, cheapest first
- 1Look at the battery terminals and cable ends for corrosion or looseness, and clean and tighten them if needed. · you can do it
- 2Check that the battery is not visibly damaged, and note whether the charge warning lamp is on while driving. · you can do it
- 3Measure battery voltage with the engine off and again with it running, using a multimeter or a free test at a parts store. · you can do it
- 4Have the battery load tested to look for a shorted cell. · mechanic
- 5Test alternator output and check the regulator, the alternator cable and the ground straps for voltage drop. · mechanic
- 6Check for parts that keep drawing current when the car is off, and clear the codes to see if P0562 returns. · mechanic
Related codes
Frequently asked questions
Can I drive with P0562?+
Short trips are usually possible, but the cause is often a failing alternator or battery. Have it checked soon, because the car could stall or not restart.
Can a bad battery cause P0562?+
Yes. A battery with a shorted cell is one of the most likely causes, along with a weak alternator.
Will P0562 fail an emissions test?+
The code is not emissions-related and does not turn on the check engine light. Still, the low voltage can set other codes, so fix it before testing.
Can I fix it myself?+
Often, yes. Cleaning terminals or replacing a battery is easy and takes roughly 0.3 to 2 hours in total. An alternator problem may need a shop.
Written with the help of AI from the public OBDex definition (CC0). Each make may use the code differently. Updated: 2026-11-10