The meaning of reduced engine power warning.

In modern cars the reduced engine power warning light comes on during a drive to cut engine power supply. This is a failsafe and then you will notice a reduced acceleration and car speed. You may not know what to do after it comes on. In order to determine the appropriate remedy, you need to know the reasons behind the engine power is reduced warning light.

Dashboard warning lights vary from one car manufacturer to another. So, what you witness as a warning light in the first car model may not be the same for the most recent car model. But there are common dashboard warning lights that are shared by all cars.

What is the reduced engine power warning light.

It’s a common warning light found in most General Motors Cars. Sometimes this warning light is coupled with the check engine light. But this depends on the programing of the car’s primary computer known as the powertrain control module PCM.

Lets find out what this warning light means and what someone can do about it.

The engine power reduced warning means exactly what those words say. There has been a limitation of the engine’s performance. This happens at a moment where the PCM has detected an issue. That being said, the PCM communicates to you that something needs to be checked out.

Thing is, the PCM programs vary from one model to another. That’s why it is essential for you to have the owners manual so that you can check what the warning means. But the owner’s manual mainly shows a general overview of what the warning is supposed to mean. Additionally, the year the car was manufactured also affects the warning’s meaning.

What does it mean when the engine power is reduced?

The PCM is responsible for monitoring the car’s operation capabilities. If the PCM detects a failure in the system, the next move is usually to cut back on the ability to accelerate. When this happens to you when you’re driving, the PCM has the ability to cut fuel delivery into the combustion chamber. Hence making it impossible to drive for a longer distance.

Most modern car models have different ways to tackle a system failure. It all depends on the manufacturer’s program on the PCM.

What causes reduced engine power?

Car engine size

There are a lot of possibilities as to the causes of the reduced engine power warning light. Secondly, as I have mentioned above, the cause of the PCM warning light depends on the year and model of the car. However, there are some common causes of the engine power reduced warning. Lets deal with each one of them.

1. Throttle body.

When the throttle body is dirty it may trigger the reduced engine power warning. For some modern cars they use an electronic throttle actuator control. The PCM uses accelerator position sensors in the throttle body to determine whether the driver can accelerate.

Afterwards, the PCM uses the throttle position sensors to execute the right throttle response. The result is the PCM uses an actuator motor to control the throttle. Then air goes into the engine and helps in production of more power.

2. Broken Circuit.

Your PCM relies on connections within the car to communicate with various components. For example, car sensors. The reduced engine power warning light comes up when there is a problem with the connection between the PCM and the throttle position sensors.

That is because at this point the PCM won’t be able to effectively execute a throttle response. Further, the actuator motor will be unable to control the suction of air into the engine.

3. Faulty Throttle Position sensor.

The throttle actuator system uses accelerator sensors that monitor the driver’s desire for accelerating. Then the PCM uses the actuator motor to control the throttle body depending on the accelerator position sensors. If these position sensors are faulty then the ”engine power reduced” warning will be initiated.

4. Faulty Accelerator Pedal Position sensors.

They are usually installed to help the PCM control the amount of air sucked into the engine. Additionally, the PCM uses these sensors to determine the power that the engine requires for acceleration. If these sensors are faulty, the car will go into reduced power mode. The sensors are usually connected to the accelerator pedal.

5. Faulty cooling system.

The car’s cooling system components are very important when it comes for engine power generation. Heat produced by the engine is capable of interfering with effective fuel combustion. If any of the cooling systems isn’t working effectively, there will be reduced engine power. Hence the ”engine power reduced” warning light on the dashboard.

6. Underlying engine problems.

This isn’t a straight forward issue and it will require further investigation. For example, a fuel pump could be faulty hence reducing the engine’s power.

7. Powertrain Control Module PCM problems.

The car is made up of interconnected networks that communicate to get data that concerns the car’s operations. If any part of the interconnected network is at fault the car could go into reduced engine power mode. Then the PCM will communicate to the driver through the dashboard warning light.

How to fix reduced engine power.

The reduced engine power dashboard warning light requires thorough investigation before diagnosis. This investigation will require a professional before the warning light can go off.

This recommendation is because there are a numerous amount of reasons why the car goes into reduced engine power mode. Furthermore there is the factor of having varying reasons behind the warning based on the car’s model and year. If you’re going to attempt to discover the cause of this warning light, there are a number of things that are recommended for you;

1. Consult the factory repair information.

There is a vast pool of information on databases that can be helpful to you. Start by specifying your car’s year and model because this will narrow down the causes. Access a repair manual and get the necessary diagnosis and repair options.

This will bring you closer to figuring out the issue but you will require additional diagnostic steps before finally conducting a repair. The repair information you get will ensure that the process of repairs doesn’t go wrong.

2. Technical service bulletins.

These technical service bulletins are offered by the manufacturer to help with diagnosis. Technical service bulletins display the common issues that may arise in certain car models. Further, they provide a guide for repair procedures matching the common issues.

There are Technical service bulletins that address specific issues like the reduced engine power mode. All you have to do is search for your specific car model and year in order to get the right guidance. For example; PIT3138A: states that Reduced Engine Power warning light may be triggered due to an electrical short inside the cooling system fan clutch. The TSB is meant for 2002-2005 Midsize GM SUVs. 

3. Check for Diagnostic Trouble Codes (DTCs)

This involves a scan tool or DTS reader. This analysis doesn’t give you a complete background of what the issues are. Instead, it points you towards the right direction for further investigations. Once the code is generated you will have to consult a repair database or manual in order to know the next steps.

Can I drive with reduced engine power warning light?

Yes you can drive when the reduced engine power dashboard warning light is on. But this is not advisable by most automotive professionals. If the light comes up when you’re driving, reduce the car’s speed and locate the next auto repair shop. It is highly recommended that you stop and have the car towed to a repair shop. That’s because the computer is communicating that something is wrong and it should be corrected.

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