Reduced Engine Power Causes And How To Fix?

Reduced engine power can be frustrating and concerning for any vehicle owner. Whether you’re on a long road trip or simply trying to navigate through city traffic, the sudden loss of power can leave you feeling stranded and helpless. Understanding the causes behind this problem is crucial in finding an effective solution. Various culprits could be responsible for your car’s diminished performance, from faulty sensors to clogged fuel filters.

In this guide, we will delve into some common causes of how power engine is reduced and provide practical tips on fixing them, ensuring a smooth and powerful driving experience every time.

What Does “Reduced Engine Power” Mean?

Reduced Engine Power Causes And How To Fix?

When you see the dreaded Engine Power message light up on your dashboard, it can be pretty alarming. The vehicle suddenly feels sluggish and unresponsive, making for a nerve-wracking driving experience. But what does this warning mean, and why does it happen?

It is a safety measure built into modern vehicles that trigger when there is a potential issue with the engine or other crucial components. It typically occurs when your vehicle’s onboard computer system detects a fault in one of the critical components that affect engine performance, such as the throttle body or fuel injection system. By reducing power output, your vehicle prevents excessive strain on the engine that could lead to catastrophic failure.

The sudden decrease in power may be frustrating for drivers who prefer speedy acceleration; it’s important to remember that this warning is there for your safety. Instead of panicking or trying to force more power out of your engine by applying more pressure on the accelerator pedal (which can do more harm than good), it’s best to pull over safely as soon as possible and call for roadside assistance or have your vehicle towed to a professional mechanic who can diagnose and repair the underlying issue causing this reduced power mode.

Understanding what Reduced or dreaded Engine Power means can help you react appropriately and take necessary actions to prevent further damage or potentially dangerous situations while driving.

Common Causes Of “Reduced Engine Power” Message And How To Fix It

This problem has several common causes, and understanding them can help you diagnose and fix it quickly. Also, by identifying the common causes of why engine power is reduced and knowing how to fix them, you’ll be better prepared for any unexpected drop in performance while driving your vehicle.

Reduced Engine Power Causes And How To Fix?

Low Voltage at Batteries

The battery supplies electrical power to various vehicle components, including the engine. When there is a low voltage, it can lead to insufficient power being delivered to the engine, resulting in reduced performance. It can be caused by various factors, such as a weak or dying battery, loose or corroded battery terminals, or a faulty alternator not charging it correctly.

Regular maintenance and inspection are crucial to prevent low engine power due to low voltage at batteries. Checking and tightening battery connections regularly will ensure the proper flow of electricity from the battery to the engine.

Alternator Failure

The second culprit behind “why engine power is reduced” is alternator failure. The alternator plays a crucial role in charging the batteries while the engine runs, so it can lead to decreased power output when it malfunctions. Signs of alternator failure include dimming headlights, dead battery, and difficulty starting the engine. 

To address this issue, you should inspect the alternator belt for any wear or tension issues. If those seem fine and other electrical components are functioning well, replacing the faulty alternator might be necessary.

Starter Motor Failure

The starter motor is responsible for initiating the engine’s combustion process but occasionally fails for several reasons, such as electrical problems or mechanical issues within its components.

To fix this issue effectively, you should perform basic checks, such as ensuring that all cables connected to the starter motor are tightly secured. If no visible fault occurs at first sight, it would be wise to examine the internal parts of the starter motor itself.

Fuel Pump Failure

The fuel pump is responsible for delivering the necessary amounts of fuel to the engine. When it starts to malfunction, it can lead to a significant decrease in power output. It often occurs due to wear and tear over time or due to contaminated fuel clogging up the system. 

To fix this issue, replacing the faulty fuel pump is usually necessary. Choosing a high-quality replacement part that fits your vehicle model for optimal performance is essential.

Ignition System Problems

The ignition system creates and delivers the spark needed to ignite the fuel-air mixture in the combustion chambers. When this process is compromised, it can lead to decreased power output and performance issues.

A common problem within the ignition system is worn or fouled spark plugs. Over time, spark plugs can become covered in carbon deposits or experience electrode erosion, causing inconsistent sparking. This results in incomplete combustion and a loss of power.

It is recommended to consult a professional mechanic who will perform tests on various ignition system components using specialized tools such as an ignition tester or oscilloscope.

Bad Spark Plugs

Causes Of “Reduced Engine Power" Message  | Bad Spark Plugs

Bad spark plugs are often overlooked as a potential cause of low engine power, but they can significantly impact performance. Spark plugs play a crucial role in igniting the fuel-air mixture within the combustion chamber. If they are worn out, fouled with carbon deposits, or improperly gapped, they may not be able to generate a strong enough spark to ignite the fuel properly. As a result, the engine may hesitate, misfire, and experience reduced power.

Regular maintenance is essential to prevent issues caused by bad spark plugs and ensure optimal performance of your engine. Inspecting your spark plugs periodically and replacing them according to manufacturer guidelines or any signs of wear and tear is recommended. You can avoid low engine power caused by faulty or failing spark plugs and keep your vehicle running smoothly.

Faulty Wiring Harness

A faulty wiring harness is a relatively common cause. The wiring harness is responsible for connecting various electrical components in your vehicle. If it becomes damaged or frayed, it can disrupt the flow of electricity and lead to a loss of power. 

Finding and fixing issues with a faulty wiring harness requires expertise and patience. Technicians may need to meticulously inspect all the wires for any signs of damage or weak connections. Also, they may need to use specialized equipment to trace electrical circuits throughout the vehicle.

Defective Coil Pack

A coil pack plays a crucial role in the functioning of the ignition system by converting low-voltage electricity into high-voltage energy, which is necessary for sparking the spark plugs. If the coil pack is defective, it can lead to weak or inconsistent sparks, resulting in low engine power.

A common sign of a faulty coil pack is misfires and rough idle. When the spark plugs do not receive sufficient energy from the coil pack, they may not ignite properly, leading to misfires and a noticeable decrease in engine power. Also, a defective coil pack can cause difficulty starting the engine or even complete engine stalling.

To diagnose this problem, you can use an OBD-II scanner to check for trouble codes related to ignition system malfunctions. Replacing a defective coil pack is straightforward and can significantly improve engine performance.

Stuck Throttle Valve

The throttle valve controls how much air enters the engine, allowing for proper combustion and power generation. If the throttle valve gets stuck due to carbon buildup or mechanical issues, it restricts airflow and decreases engine output.

Addressing a stuck throttle valve is essential to prevent further damage to your vehicle’s engine. Suppose you notice reduced power or difficulty accelerating. In that case, having your vehicle inspected by a qualified mechanic who can diagnose and fix any issues with your throttle system efficiently is advisable.

Systems That Can Cause Reduced Engine Power

It is crucial for vehicle owners to regularly inspect these critical systems as neglecting maintenance could lead to a chronic reduction in engine power and potentially more severe damage. 

By addressing issues promptly and keeping these systems in check through routine maintenance, drivers can ensure that their engines perform at their peak capability for extended periods. Reduced or low engine power can be attributed to several different systems in a vehicle. 

Systems That Can Cause Reduced Engine Power

Poor fuel quality

Contaminated fuel can lead to clogged fuel injectors and decrease the overall efficiency of combustion within the engine. It can result in reduced horsepower and sluggish performance. It is crucial to ensure that you use high-quality fuel and regularly maintain your vehicle’s fuel system to avoid problems caused by poor fuel quality.

Inadequate airflow

The air filter is vital in supplying clean and unrestricted air to the engine for combustion. If the air filter becomes dirty or clogged, it hinders the airflow, reducing power output. Regularly checking, cleaning, or replacing your air filter can help maintain optimum airflow, maximizing your engine’s potential.

Excessive Exhaust Back Pressure

When there are restrictions within the exhaust system, such as damaged catalytic converters or blocked mufflers, it restricts the efficient exit of exhaust gasses from the engine. This excessive back pressure interrupts proper combustion and forces the engine to work harder, compromising performance.

Overheating Issues

Overheating can occur for various reasons, such as malfunctioning cooling systems or low coolant levels. When the engine overheats, it can cause severe damage like warped cylinder heads or blown head gaskets—the ensuing loss of compression leads to a significant decrease in power production.


Reduced engine power can be caused by various factors, including issues with the fuel system, ignition system, or exhaust system. Diagnosing the specific cause of reduced or low engine power is essential to fix the problem effectively. It can be done through visual inspection, diagnostic testing, and professional help.

Regular maintenance and prompt attention to any signs of low engine power can help prevent more severe damage to the engine and ensure optimal performance. By addressing and fixing these issues promptly, you can enjoy a smoother driving experience and extend the lifespan of your vehicle.


Can I drive with a reduced engine power warning on?

Driving when engine power is reduced, a warning can be risky and is not recommended. When the low engine power warning comes on, the vehicle’s computer has detected a fault in its performance and has limited its power output to protect it from further damage.

It can decrease acceleration, lower top speeds, and difficulty maintaining speed. It is best to pull over safely and have your vehicle inspected by a professional mechanic to determine the cause of the warning and address it accordingly.

How Much Does it Cost to Fix Reduced Engine Power?

It is recommended to consult with a trusted mechanic or dealership to get an accurate estimate for fixing the reduced or low engine power in your specific vehicle. They will be able to provide you with a detailed breakdown of the costs involved based on their assessment of the issue.

Zaheer Khan