Reduced Engine Power – Main Causes & Fix


Do you feel like your car has reduced engine power? Here are all the main causes, what you can do to fix it and how much it costs to repair if required. You are in the middle of overtaking an 18-wheeler on a 2-way road. There’s another truck coming in front of you, but you have time to finish your maneuver. Then, you lose power. Scary, isn’t it? Reduced power is the cause of many accidents while overtaking, but don’t worry, you will learn how to handle it below. Let’s get started!

Reduced Engine Power Warning Meaning

Reduced Engine Power – Main Causes & Fix

When this light appears, it means that the performance of your vehicle is limitedYour car’s electronic system detects a system failure and makes it visible on the dashboard. It can also make your engine work at a lower range of power.

Reduced power affects gear shifting and revving in. This is called fail-safe mode because it takes pre-defined values to allow your car to reach home. When the failure is too much, it can even prevent your car from turning on by cutting power to the fuel system so it doesn’t catch on fire. This one is the limp mode, and it can be one of the reasons your car is not turning over.

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Causes Of Reduced Engine Power Warning

Reduced engine power warning is often caused by malfunctioning engine sensors, such as the oxygen sensor, MAF sensor, or a broken throttle body (intake issue). It can also be caused by a loose connection to any of these sensors (electrical issue). A clogged catalytic converter is also frequently to blame (exhaust issue).

As you can see, lack of engine power can be caused by so many reasons, so, avoid replacing parts without a proper test. The best way to determine what is causing a Reduced Engine Power Warning is by checking its trouble codes with an OBD2 scanner. It’s usual to find a trouble code stored in the system when your car shows a warning sign. This can save you a lot of money, as it shows where the issue is.

1. Loose Connection

Reduced Engine Power – Main Causes & Fix

Every important component in your vehicle is connected with wires. If there is a short in the electrical system, an unexpected resistance, or one of the wires is damaged, your engine will go into fail-safe mode. A loose connection is simple to fix, but it may become very difficult depending on the place it happened. Some places require more dismantling than others.

2. Defective Oxygen Sensor

Oxygen sensors, also called Lambda sensors, measure how much oxygen is leaving the system by way of the exhaust. If there is too much or too little oxygen coming out, the ECU will adjust the air-fuel ratio to balance performance.

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A defective sensor will send the wrong parameters back to the ECU, causing wrong adjustments to the fuel-air mix. This will reduce your car’s performance, cause engine issues and also trigger a Reduced Engine Power Warning.

3. Throttle Body Issues

Reduced Engine Power – Main Causes & Fix

The throttle body is full of parts that can break and lead to these warnings. First of all, the butterfly valve is a mechanical valve that allows fresh air to flow into the engine. When this valve breaks or gets clogged with carbon, it won’t open properly.

If your engine cannot get enough air, it will misfire and sputter while causing warnings on the dashboard. The throttle position sensor that must also work properly to allow free movement of the air is also near this valve.

This sensor detects the position of the gas pedal and tells the computer to open the butterfly valve based on that. If this sensor is faulty, the valve will not get the appropriate data, and airflow will be reduced.

4. Malfunctioning ECU

The Engine Control Unit is your engine’s brain. Every onboard sensor communicates what is going on with the ECU so it can perform proper adjustments. If the air-fuel mixture isn’t right, it’s the ECU task to adjust it for better performance.

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When the ECU fails, countless issues can happen. You might start noticing poor performance because of the engine compensating for problems that may not even be happening.

This is one of the most expensive faults you can find, as it can easily go beyond a $1.000 repair.

5. Failing Mass Airflow Sensor

Reduced Engine Power – Main Causes & Fix

The mass airflow sensor is between the intake manifold and the air filter. It measures the pressure and density of the air that gets into the engine by comparing temperatures.

The ECU gathers this information to apply the proper fuel-air ratio. When the MAF sensor fails, it sends wrong data, which creates issues in the fuel mix and causes warning lights to come to life.

6. Clogged Catalytic Converter

The catalytic converter is right after the exhaust manifold. Its purpose is to convert poisonous exhaust gases into less harmful contaminants. If the engine hasn’t been running properly, for example at low revs, or has been mainly working inside a city, the catalytic converter will become clogged.

The age of the vehicle also matters to this fact. When this happens, your car will perform poorly at emissions tests, and you will lose a lot of power. This happens because your car won’t be able to throw away burned gases. It won’t always light the Reduced Engine Power Warning, but it will always light the Check Engine Light.

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7. Transmission Failure

Reduced Engine Power – Main Causes & Fix

Transmission issues are awful to deal with and can lead to many headaches. If the transmission is slipping because of having a worn-out clutch, or has low fluid (in automatic cars), it will cause some error codes and power loss in the wheels.

Reduced Engine Power Warning Repair Cost

Reduced Engine Power – Main Causes & Fix

The cost to repair a Reduced Engine Power Warning ranges from $0 to $2,500. The only way to know the exact cost is to learn what’s causing it.

Using an engine code scanner will help you find where the fault is. The OBDII scanner will read any fault codes, showing you what systems might be to blame, but it can lead to mistakes at times.

Only use this tool if you are familiar with this technology. Otherwise, it’s better to ask your local mechanic to check your fault codes. Ideally, you would notice a loose connection, which wouldn’t cost you anything to fix if you can fix the link.

Replacing your catalytic converter or swapping out the ECU is an expensive fix that might end with your vehicle heading to the junkyard. You should never drive with a Reduced Engine Power Warning light. If Fail-Safe Mode has been activated, you must immediately drive to a safe location and turn it off.

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Turn on your hazard lights to let other drivers know you are having trouble, and drive on the outer side of the road so you avoid any crashes. If you have more than a few miles to drive, it’s better to have your vehicle towed to the nearest garage instead. Forcing your car in this situation could end in a more serious breakdown or even a deadly crash.

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