Toyota Prius: P0562 – System Voltage Low

Common OBD-II trouble codes include P0562.  It’s a general code, which means that it means the same thing for any vehicle, including the Toyota Prius.  P0562 It means that the system voltage drops below 10 V for more than a minute.  With the engine running, the system voltage should be 14.1-14.4 volts, and it’s typically caused by a bad alternator.  It’s very common to get the battery light with P0562.

P0562 Quick facts

• P0562 is triggered whenever your Prius’s voltage drops below 10 volts for over a minute straight.
• With the engine running, ideal voltage should not exceed 14 volts
• There is usually no obvious sign.
• Most often, it is caused by an alternator problem.

P0562 Symptoms:  Toyota Prius

If P0562 is the only code your Prius has, there typically aren’t any noticeable symptoms.Other than the check engine/battery lamp.  If your battery voltage falls too low, you may experience symptoms.

If you do experience symptoms, it’s due to battery drain.  it is very likely that your Prius wouldn’t even turn back on if you tried.  Your battery may not be able to turn on the starter because it has been too low.

Below are the top P0562 symptoms:

• Verify Engine LiabilityGht– This is the most common symptom, and often the only symptom.
• Warning/Low Battery Light–  You’ll more than likely get the battery light with this code.
• Poor Fuel Economy–  This can occur when your Prius’s engine and computer are not getting enough voltage.  This could mean that the computer is unable to control ignition timing and fuel mix.  Oder, it may be too weak.
• Failure– Without enough voltage to fire the spark plugs properly, the motor will sputter and cough.  If there is enough misfire, the check engine lamp may flash.
• Problems shifting– Today’s modern automatic transmissions are computer controlled.  Without enough voltage getting to them, they won’t be able to respond to the engine RPM and vehicle speed in a timely manner.
• Won’t Start– A very common situation with P0562 is running the vehicle and everything is operating fine, and the check engine light comes on (battery light too, usually).  You get the vehicle home and when you go to drive it again it won’t start.  It is most likely that the alternator has failed.  

P0562 Causes + Diagnosis:  Toyota Prius

These are some of the leading causes for P0562.

1. Alternator

The alternator supplies voltage to the battery and to all of your Prius’s electrical system while it is running.  It can also cause P0562 if it is damaged.  If it goes all the way bad that’s make diagnosing the code relatively easy.  The vehicle won’t start if it runs too long with a bad alternator.  How long it would take to drain the battery all the way is going to depend on the battery’s age and driving conditions.

It’s when the alternator begins to intermittently fail it can be tricky to diagnose.  Many auto parts stores can test your alternator free of charge.  They will also be able to replace your alternator if you need it. It is quite affordable.  You should also change your serpentine belt.

Toyota Prius Alternator Diagnosis

2. Voltage regulator

In order to prevent the charger from overloading, it ensures that the required voltage level is maintained.  This regulator prevents too much voltage from flowing and can throw P0562.

3. Wiring of batteries

There’s a lot of wiring associated with your Prius’s charging system.  The following wiring should be checked for corrosion, fraying, or poor connections.

• Batterie Terminals– The battery terminals, if left alone long enough, will corrode on any vehicle.  When this happens it’s difficult for the charging system to function properly.
• Wiring an alternator for a battery– Take a look at the wiring from the alternator to the battery.  Check to make sure it is not frayed or damaged.  Be especially careful with parts that come in contact with other parts of the engine.
• Ground Wire– The ground wire that bolts to the negative battery terminal will bolt to the chassis or engine block.  You must ensure that your connection is secure and free from corrosion.
• Connect PCM to an Alternator– Check to see if the wiring going from the alternator straight to the PCM looks good.  The wiring harness has a lot of distance to travel and can be damaged even if it is well protected.  The wiring harness's connection to the motherboard should be checked for fraying.  It is not the most common wiring problem on our list. You should not pursue this issue if you are unable to find any other solutions.

4. Bad Battery

While a bad battery can throw P0562, it’s not nearly as likely as an alternator or wiring issue.  Before replacing it, you should test it.

5. Massive Battery Loss

If your vehicle has aftermarket equipment such as a very high watt stereo system, winch, or something else, it could be placing such a heavy load on the charging system that you’re getting P0562.  It should take at most a minute for the code to be thrown.

A major power draw can occur if there is a problem.  It can happen when something is shorted and pulls too much current.

Toyota Prius Battery Drain Diagnosis

Conclusion:  P0562 Toyota Prius

It can be difficult to track down P0562.  It’s usually the alternator that is at fault.  You can add anything to this article.  Good luck fixing your Prius!