Prius All Warning Lights On (Explained)

The Prius, like other vehicles, has several warning lights that tell the driver if there’s something wrong with the vehicle. When there is something wrong with the engine, the check engine light will appear. If there’s something wrong with the brakes, a red brake light warning will appear. When every light on your dashboard suddenly appears, it means there is an issue with the battery or the alternator.

All The Warning Lights Turned on at Once! What is Going On?

You are driving down the street as you normally would, and suddenly all the warning lights in your Prius turn on at once! What does it mean when every single warning light on the dashboard and the computer system goes off at once?

Is your vehicle about to explode? Should you jump out of your moving vehicle like an action hero? Is it a bad glitch designed to induce a panic attack?

Here’s the meaning of every warning light on a Prius going off at once.

When all the lights go up at once, it can either be one of two problems causing this issue. It can either be an issue with the alternator or an issue with the battery charging system.

When all the warning lights in your previous go up at once, remain calm and pull over to the side. If you can, return home while driving as slowly as possible. Also, call your Prius-certified mechanic so they can direct you on what to do. If the drive is too far from your home to your mechanic shop, they may tow your vehicle to the previous shop for a fee. 

Issues With the Alternator

The reason every light goes out at once is to show the driver that an alternator or battery charging issue is in trouble. Problems with the battery and the alternator are dire issues that require attention immediately. 

So, when there is a problem with the alternator, cancel everything you have to do for the day and head directly to your mechanic.

When there is an issue with the alternator, your vehicle is in danger of shutting down, even if you are going 55 mph on a freeway.

Here are two signs that will confirm your alternator is the issue causing the warning:

All the lights in your Prius are dimming or Far Too Bright. 

When the alternator is slowing down or failing, it will either exert more power than it usually does or it cannot provide enough power. When your Prius exerts more power, the lights in the vehicle will be much brighter than usual. 

On the other hand, if the alternator is failing slowly, then the lights will dim lower and lower as the days pass by.

It will take you more than a few times to turn on the engine. 

Everyone expects their vehicle to turn on when they put the key in the ignition and turn the key. But when an alternator breaks down, the ignition will not turn on the vehicle during the first key turn. 

You may need to warm up the ignition spark a few times before the ignition finally activates the engine. 

Repair or replace the alternator

Hopefully, your alternator isn’t so badly damaged, and you can pay a mechanic to repair it. If the alternator is too far gone, then you will have to replace it, and replacing the alternator is far more expensive than repairing it. 

On average, the price of a brand-new alternator is between $200 and $350. Then, you will have to pay your mechanic at least $150 to install the new alternator. 

You may spend up to $500 replacing the alternator. And this price is for older Prius models. If you have a more expensive and newer car, like the Prius models that came out in the last 5 years, it can cost $1,000 to replace an alternator. 

Repairing an alternator can be as low as $100. The price of repairing the alternator is determined by how damaged it is.

If repairing the alternator rises above $250, you might as well spend the extra money and replace it together.

Issues with the battery

If the battery in your Prius doesn’t work, you aren’t going anywhere. There are two batteries in a Prius, the traction battery and the 12V battery.

The battery warning light will appear on the dashboard. Obviously, every warning light going off means that the battery warning light will also go off at the same time. But the battery warning light will start flashing days before all the warning lights turn on at once.

Moisture is preventing the battery from flowing correctly

If there is humidity or moisture spilling out of the engine, then moisture and small water droplets are gathering on the battery. You probably know this already, but it is a terrible idea to have your battery come into contact with water.

Most likely, the water is coming from the air conditioning units or the coolant system. The moisture will seep around the cables and cause corrosion. 

The Prius’ battery is nearing its end of life.  

For Prius’ battery, the main traction battery burns out between 8 to 10 years. So, if you’re closing in on the 8th year, then save up for a new battery. Prius models can last up to 12 years, but you will definitely notice the battery performing poorly.

Replacing the traction battery of a Prius will cost you a good amount of money. The traction battery can cost up to $2,000 and that’s not including the cost of labor. The total cost to replace a traction battery is about $2,200 and $4,500.