"Check Hybrid System" Warning (5 Causes and How to Reset)

Hybrid vehicles have an electric motor as well as a combustion engine like a traditional vehicle. Hybrids are the best of both worlds, using the combustion engine for long range and regenerative braking for increased efficiency in the city.

While hybrid vehicles offer significant advantages over vehicles that strictly have a combustion engine or an electric powertrain, they can experience issues just like any other technology.

One such issue is a “check hybrid system” warning light. Here are some tips for troubleshooting the warning light.

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What Does “Check Hybrid System” Mean?

The Check Hybrid System warning indicates that a fault has been detected in the vehicle’s hybrid system. This fault could be related to the battery, a computer that manages the hybrid system, or the electric motor.

This message is commonly found on the Toyota Prius, but you may experience the warning on other hybrid vehicles as well. Sometimes the issue is as simple as a blown fuse. The warning will typically be accompanied by a check engine light.

Causes of Check Hybrid System Warning

1) Bad Hybrid Battery

Batteries age over time. They hold less charge, and eventually they will stop working. If you have an older Prius or other hybrid vehicle, chances are good that your hybrid battery will need replacing eventually.

While this is a pretty expensive fix at the mechanic, ChrisFix has a great video on YouTube that shows how to replace the hybrid battery yourself if that is something you would be comfortable doing.

2) Bad 12V Battery

The 12V battery is a conventional car battery and is not specific to hybrid vehicles. Sometimes a problem with the 12V battery can cause a Check Hybrid System warning.

If you suspect your 12V battery is bad, replacement is pretty easy. Some auto parts stores may offer a service to do this for you, but it is also easy for many people to do on their own.

3) Bad Inverter

An inverter converts the DC power from the hybrid battery into AC power for the electric motor(s). When your inverter goes bad, your vehicle will not be able to adequately deliver electric power to the wheels.

4) Wiring Issue

Hybrid systems come with more electrical components, and that means more wiring and ground points. A severed wire or bad ground could cause a warning light or render the hybrid system inoperable.

To search for a bad wire, it is always best to have a wiring diagram handy from the manufacturer. Some vehicles may be prone to corrosion or bad wiring in certain areas. When rodents make their way into your vehicle, sometimes they chew wires, which can cause faults and error codes as well.

5) Blown Fuse

A blown fuse is the cheapest and simplest fix to a warning light, so always check for blown fuses when troubleshooting an issue. Most fuse boxes are either found in the footwell of the vehicle or under the hood.

Can You Drive with “Check Hybrid System” Message?

There are many cases where your car will stall while driving and fail to start on just the gasoline engine when you see this message. In this case, you may have to solve the root cause of the issue, or reset the warning at the very minimum to get your vehicle running again.

If your car is otherwise running OK, it’s often safe to proceed to your destination even with the warning illuminated. This will depend on the exact cause of the issue, of course.

If you have any doubts on whether your vehicle is safe to drive, it’s always best to bring the vehicle to a qualified mechanic. Sometimes they can do a quick diagnostic to assess the roadworthiness of the vehicle.

How to Reset Check Hybrid System Warning

This video nicely outlines one method of resetting the hybrid system. In some cases, this may clear your error message:

Turn the vehicle off, then pop the hood and open the trunk. You will find the hybrid battery in the trunk near the spare tire. On the hybrid battery, there is an orange safety interlock switch. Remove this by sliding the handle toward the left side of the vehicle, then pulling out.

Next, make your way to the hood and open the fuse box. You should see a large wire with a white connector at the end. Disconnect the white connector from the fuse box.

Wait 10 minutes with both components unplugged, then reinstall them in reverse order. Turn the engine on and off 3 times. This should clear the warning light in many cases. If your warning light has not cleared, you may have a more permanent issue with your battery or hybrid system.

Do note that this may not fix the root cause of your issue, so don’t be surprised if the warning light returns in the future. The Check Hybrid System light may appear because you have a battery that still works intermittently, but is close to complete failure.

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Sean

Sean is an avid car enthusiast who maintains his own personal fleet of vehicles and wants to help others do the same. He has received many hours of professional driving instruction, is a member of the SCCA, and takes the art of driving seriously. Thoughtful, skilled driving has the potential to save many lives. Sean can often be found at the race track, autocross course, or hillclimb event.

“Check Hybrid System” Warning (5 Causes and How to Reset)