Reduced Engine Power Causes And How To Fix

If your car doesn’t speed up as it should, the “engine power reduced” light on your dashboard may also be on. When the Engine Power Reduced warning light comes on, your car can’t go as fast as it could. Bad sensors or a broken transmission can cause a reduced engine power warning.

Depending on what’s causing the problem, there are many ways to fix it, such as checking the battery and changing the fluids. Do you think your car’s engine has less power? Here are the most common reasons, what you can do to fix it, and how much it will cost if you need to fix it.

What does Reduced Power Warning mean?

The PCM notices a problem with your car’s engine and tells the message to light up. With the warning message, the engine might need to be fixed. Because there is less power, the car might not shift, and you might be unable to speed up.

In the worst cases, the PCM will cut off fuel to the engine, making the car stop running. Some people call this system “fail-safe mode.” But it’s also called “limp mode” because the warning gives you enough time to get home without hurting the engine or transmission anymore.

What Causes Reduced Engine Power?

Many different things can cause the “reduced engine power” warning, so you should never replace parts you think might be broken. If your dashboard gives you a warning, you can look in your owner’s manual to determine what it might mean for your particular make and model.

Many companies include detailed information about warnings to help you figure out what’s wrong. Bad engine sensors, like a bad oxygen sensor, MAF sensor, or throttle body, usually cause a reduced engine power warning. It can also be caused by these sensors not being properly connected. A clogged catalytic converter is another common cause.


Fault in Throttle

Both newer and older cars with internal combustion engines need a physical throttle so that air can get into the engine. In the throttle body of your car, there is a butterfly valve that opens and closes to let air into the engine. When carbon builds up on the throttle valve, it can get clogged and stop the throttle from opening all the way.

If the throttle body is broken, it will limit the amount of air that can get into the combustion chamber. This will make the engine less powerful and make your car’s “reduced engine power” light turn on.

Inaccurate Oxygen Sensor

The oxygen sensor in a car measures how much oxygen is leaving the car through the exhaust. They also help adjust the mix of air and fuel so the engine can burn properly. If one is broken, your “check engine” light and “reduced engine power” light may come on.

But a broken sensor can send wrong information back to the computer, which can make changes that shouldn’t be made. This causes an imbalance in the air-fuel mixture, which not only leads to poor performance and engine problems but can also cause the Reduced Engine Power Warning to go off.

Loose Connections

Wires link all of your car’s major parts together. If the electrical system has a short or one of the wires is broken, the engine could go into a fail-safe mode. This problem can also happen if a clamp is loose or a ground wire isn’t fastened properly.

When wires are broken or connections are bad, the TAC (Throttle Actuator Control) system can’t work properly. This problem can cause several issues with a car, such as an engine going into reduced engine power mode. Your car is full of plugs and wires that power all of its parts and keep it running. A short in the electrical system, a loose ground wire, or a loose clamp is enough to cause problems with your vehicle.

Damaged ECU

The Engine Control Unit (ECU) is what makes everything work. All the sensors tell the ECU what’s going on so that the right changes can be made. For example, if the mixture of air and fuel isn’t right, the ECU changes to make the car run better. But many things can go wrong when the ECU starts to break down.

You might start to notice that the engine isn’t running as well as it used to while it tries to fix problems that might not even be there. The “reduced engine power” light might come on if there is a problem with your car’s ECU, which could be one of the worst and most expensive problems.

Clogged Catalytic Converter

After the exhaust manifold, the catalytic converter is attached to the car’s underside. Its job is to turn carbon monoxide into carbon dioxide by reducing and oxidizing it. This cuts down on the number of harmful emissions. However, it is against the law to drive a car without a catalytic converter; if it gets clogged, the car will fail an emissions test. The catalytic converter can get clogged if the engine isn’t running right or the car is getting old.

When this happens, not only will the car fail an emissions test, but the engine will not run as well. It won’t always show the Reduced Engine Power Warning, but at the very least, the Check Engine Light will be on.

Faulty Mass Air Flow Sensor

The mass airflow sensor is between the engine air filter and the intake manifold. The mass airflow sensor tells the engine control unit (ECU) how much air goes into the engine. After these measurements are taken, the data is sent to the ECU to use the right fuel-to-air ratio. When the MAF sensor breaks, it sends the wrong data, messing up the ratios and making the warning lights on.

Most of the time, a bad MAF sensor will cause the engine to have less power all the time. This may be more noticeable when you accelerate harder than usual, like when you merge onto the highway. In many cases, the problem can be fixed by cleaning the sensor. Make sure that the product you use to clean the sensor is the right one.

Transmission Problem

Transmission problems are never fun to deal with and can cause many problems. You should expect to see some error messages if the transmission is sliding or the fluid level has dropped. While most people do not associate a decrease in engine power with transmissions, the two systems are inextricably linked. If none of the other suspects is to blame, it is time to investigate the transmission.

What to do when the reduced engine warning light turns on?

If you take it to a professional mechanic, they can figure out what’s wrong and tell you how to fix it immediately. Don’t freak out if you’re driving and the warning light for low engine power comes on. It’s not the end of the world, but you should probably pull over somewhere safe and call your mechanic before going any further.

How to fix reduced engine power?


There are times when you can solve the problem on your own. If you are handy, you might be able to fix the throttle or the catalytic converter without much trouble. Depending on the problem, you may need different tools and supplies.

You’ll need a screwdriver and a wrench to tighten connections and remove car parts so you can clean them. You need a jug of the right fluid when you change your transmission fluid.

First, look over the car

Check your car to see what might have caused the warning about low power. You can tighten loose connections yourself. If the throttle body is at fault, you can clean it. You can also replace the catalytic converter and save a little money on labor. Also, you can replace broken wires or clamp them back to their connections.

Give the battery a try

If you don’t have a multimeter, you can test the car’s battery at an auto parts store. The results will tell you if the battery is still good enough to run your car or if you need a new one.

Change the fluid in the transmission

Since the engine and transmission work together, changing the fluid is always a good idea. If you can’t figure out why the “reduced power” warning is coming on, you might want to change your transmission fluid.

The repair cost of the reduced engine power


A Reduced Engine Power Warning can cost anywhere from $0 to $2,500 to fix. The only way to know how much it will cost is to figure out what’s causing it. You should be able to notice a loose connection, which won’t cost you anything to fix if you can get the link back up and running.

But replacing the catalytic converter or ECU could be a very expensive fix that could send your car to the junkyard.


Many things could cause your engine to lose power. In many cases, the engine electronically lowered its power to protect itself from damage. You should never drive when the Reduced Engine Power Warning light is on. If Limp Mode has been turned on, you should drive the car to a safe place and turn it off right away.

If you have to drive more than a few miles, you should have the car towed instead. You don’t want to run out of power and get stuck on the side of the road or cause an accident.

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