P0562 — System Voltage Low
P0562 usually means the charging system is not keeping up. The car is running on stored battery charge, and when that is gone it will stop — often somewhere inconvenient.
The vehicle runs on stored charge until it is exhausted, then stops — including power steering and brake assist on some vehicles. Drive directly to help, not on a journey. This code will cause an emissions test failure.
What P0562 means
Every module on the vehicle depends on stable supply voltage, and the engine module monitors it. P0562 means the voltage it sees has fallen below the acceptable threshold with the engine running, which normally indicates the alternator is not charging rather than that the battery is flat. The distinction matters: a battery flat because the alternator has failed will strand the vehicle again shortly after a jump start, and low voltage sets confusing codes across unrelated systems.
| System | Electrical — charging and supply |
|---|
Symptoms you may notice
What causes P0562
Alternator not charging
A failed regulator, worn brushes or a damaged winding stops the alternator generating. The vehicle then runs on the battery alone and stops when it is empty. This is the most likely cause when voltage is low with the engine running.
Drive belt slipping or broken
A glazed, loose or broken belt means the alternator is not being turned. On many engines the same belt drives the water pump, so this can cause overheating at the same time.
Corroded or loose battery and ground connections
Resistance at a terminal or a ground strap drops the voltage the modules actually see, even with a healthy alternator. Cheapest possible cause and worth checking first.
Battery failing internally
A battery with a shorted cell loads the charging system and never reaches proper voltage. Test the battery and the alternator together, because each can make the other look faulty.
Common misdiagnosis
Replacing a battery without testing the alternator is a common and expensive loop: the new battery goes flat within days.
How to diagnose it
Measure voltage with the engine running
Measure across the battery terminals at idle. A charging system in good order holds well above the resting battery voltage; a reading at or below it means nothing is being replaced.
Inspect the drive belt
Check the belt for glazing, cracking, correct tension and that it is present at all. A slipping belt often squeals under electrical load.
Safety
Never inspect a belt with the engine running. Keep hands clear of the belt path entirely.
Check battery and ground connections
Clean and tighten both battery terminals and the engine and body ground straps. Measure the voltage drop across each connection under load.
Test the battery and alternator under load
Have both tested together. Testing either alone can produce a misleading result, because a failing battery loads the alternator and a failing alternator flattens the battery.
Related codes
Common questions
Can I just jump start it and drive?
If the alternator has failed, a jump start only buys the time the battery holds. The vehicle will stop again, and possibly in traffic. Drive to help, not onward.
Why are unrelated warning lights on?
Modules misbehave when supply voltage is low, so codes appear across systems that have nothing wrong with them. Fix the voltage first, then re-scan before diagnosing anything else.
Do I need a battery or an alternator?
Have both tested together. A failing battery makes a good alternator look weak, and a failing alternator flattens a good battery, so testing either in isolation is how people end up buying the wrong one.
Last verified 2026-07-27 · Sources: SAE J2012 — Diagnostic Trouble Code Definitions and Failure Type Byte (SAE International)
This information is for general guidance and is not a substitute for professional diagnosis. Cost figures are estimates, not quotes.