Reduced Engine Power: What It Means & How To Fix It

Whether you’re driving to work, taking your children to school, or heading out on a date, the last thing you need is to press down on your vehicle’s accelerator and have your engine barely whimper.

While you may panic at having reduced engine power, it’s important that you don’t. Since it may or may not mean a major repair is around the corner, here’s what you need to know.

What Does Reduced Engine Power Mean?

When your vehicle’s engine has reduced power, you’ll notice your “Check Engine” and “Engine Power Reduced” warning lights coming to life on your dashboard.

The warning light for “engine power reduced” or “engine power is reduced” indicates that the vehicle’s electronic control unit (ECU) has detected a problem and has entered a fail-safe mode to protect the system from damage by limiting its performance.

While this may sound bad, it’s actually good that your car is telling you this because it means that the vehicle is being protected until you can have it checked out by a mechanic!

If you are lucky, the problem may only require you to change your spark plugs, spark plug wires, or other relatively simple maintenance tasks. Unfortunately, it could also mean your engine has a severe problem that could require a very expensive repair job.

Whatever the case may be, continuing to drive time after time with these warning lights alerting you to a problem almost guarantees you’ll be spending hundreds or thousands of dollars on an engine repair job.

What Causes Reduced Engine Power?

When your vehicle suffers from reduced engine power, it can be due to one of many reasons.

One of the most common involves a problem concerning your vehicle’s TAC, or Throttle Actuator Control system. Common in today’s highly-computerized vehicles, this means there could be an issue with the throttle position sensors that are used to determine when you want to accelerate.

Should one or both of these sensors be defective, the ECU is then unable to maneuver the throttle via the actuator motor, which leads to reduced airflow inside the engine.

In some situations, you may have a problem with the accelerator pedal assembly, so this needs to be checked out ASAP!

If you’re fortunate, you may only have a loose clamp or wire within your car’s electrical system. While it may take a bit of detective work on your part or from your mechanic, this is generally not a major repair.

Other possibilities include a faulty oxygen sensor or a connectivity issue with your battery, neither of which are extremely serious. Also, reduced engine power may be due to issues with your transmission, such as a clutch that’s slipping or even just low levels of transmission fluid.

When your catalytic converter is clogged and can’t convert carbon monoxide into carbon dioxide, this can create problems with airflow within the exhaust system, which eventually make their way to your engine.

As for what can be a serious problem, this would involve having a faulty Electronic Control Unit itself. When this occurs, it is a dire situation for you and your vehicle, since getting this replaced is extremely complex and expensive.

In some cases, this repair can be so complex and expensive that it may make more sense to get a new vehicle.

Driving with Reduced Engine Power

Now that you have been advised as to the many possibilities as to why your car has reduced engine power, you’re no doubt wondering if you can still drive your car with reduced engine power. To put your mind at ease, the answer is yes.

However, before you decide you don’t need to bother getting this problem checked out right away, it’s important to keep in mind what driving a car with reduced engine power will be like once you hit the road.

For starters, your gas mileage will drop significantly, resulting in you spending much more on gas than you otherwise would under normal circumstances. Also, your acceleration will be very poor and inconsistent, which could make it difficult and maybe even dangerous if you need to drive at higher speeds.

Finally, if you have a car that requires you to shift gears, expect this to feel more like a tug-of-war at times. Also, depending on the type of ECU your vehicle has, it may disable your radio or other components deemed to be “non-essential.”

Rather than put you and your vehicle through this unnecessary strain, it’s best to visit your mechanic, find out the problem, and get it resolved as soon as possible.

How to Fix Reduced Engine Power

If you feel comfortable doing so, you may be able to take care of your vehicle’s reduced engine power while it’s parked in your driveway or garage.

When the “Reduced Engine Power” light comes on, this means the car has a problem with a certain part or system. However, it may also mean there is a circuit, connector, or harness that may be triggering the ECU.

To start with, check your battery to see that it is properly connected. If it’s not, this can lead to reduced engine power. Also, a bad ground connection to your engine could be to blame, since a drop in voltage and currents will impact your engine.

If you want to check your engine grounds, you’ll need to use a digital multimeter.

But first, you need to turn off the ignition switch to your vehicle, unplug the connector and examine it for dirt or corrosion, pull on the wires to see if any are loose and check both connections on wires to make sure they are good.

Should you not be able to enact any repairs on your own, take your vehicle to a mechanic you know and trust. When you do, the mechanic can use state-of-the-art digital scanning equipment to pinpoint the exact problem, explain it to you, and give you an estimate regarding repair costs.

How to Reset Reduced Engine Power Light

When you’re trying to figure out how to reset your vehicle’s “Reduced Engine Power” light, don’t bother looking for a button nearby or a magic wand in your glove compartment, since neither exists. 

To remove this message from your dashboard, the underlying problem will need to be pinpointed and corrected by either you or your mechanic.

Until then, this message and the “Check Engine” message will be staring you in the face each time you get behind the wheel.

How Much Does it Cost to Fix Engine Power Reduced?

Like most maintenance and repair tasks that crop up with your vehicle now and then, it could cost you next to nothing to fix this problem, or instead cost you thousands of dollars that may have you thinking about buying a new vehicle instead.

For example, if you find the problem to be your battery not being properly connected or a wire that’s worked its way loose, you won’t have to spend a penny to fix these issues.

However, if your problem involves the ECU itself, a bad catalytic converter, or a problem with your vehicle’s transmission or throttle assembly, these repairs will be more costly and need to be done by experienced mechanics.

Should you need a new throttle body, position sensor, or other similar parts, you can expect to pay around $500 for parts and labor.

As for replacing your catalytic converter or the ECU, these repairs can often be in the range of $2,500 or more, which may have you thinking twice about whether it will be worth the effort.

What if My Vehicle Doesn’t Have a “Reduced Engine Power” Warning Light?

Even if your vehicle does not have a “Reduced Engine Power” light on its dashboard, it will almost certainly have the “Check Engine” warning light to warn you of a problem with your engine.

If you think your engine is operating at reduced power, there are some simple things you can check to see if they are behind the problem.

First, check to see if your vehicle has a clogged air filter. Also, check your tire pressure. If it is too low, this can lead to reduced fuel efficiency and a noticeable difference in how your car feels on the road.

Finally, take a look at your fuel pump, or have your mechanic do it for you. In many cases when cars run sluggishly, won’t start at all, or you know there is a problem but have no warning lights at all illuminated on your vehicle’s dashboard, the fuel pump may be the problem.

If so, this will cost several hundred dollars to replace.

What is “Limp-In” Mode?

If your car is suffering from a very bad case of reduced engine power, it is possible the transmission system will go into what’s known as “limp-in” mode. Should this happen, your car will do just as this sounds and limp back to your home or to the nearest mechanic.

Occurring with automatic transmissions, you may have very limited functionality. For example, you may only have first and third gears available to you, or the transmission may lock into second gear only.

In some instances, it is possible to have access only to second gear, Park, Reverse, and Neutral.

When you’re dealing with these scenarios, it often signals that a serious problem with your vehicle exists and should be pinpointed and repaired as soon as possible so that further damage does not occur.

Frequently Asked Questions (FAQs)

Can the Cold Cause Reduced Engine Power?

If you live in a part of the country that has lots of very cold weather, it is possible your reduced engine power issues could be related to the cold temperatures outside. In some vehicles, particularly Chevrolet models such as the Malibu, cold temps have been found to adversely affect the vehicle’s throttle body system.

Does Low Oil Cause Reduced Engine Power?

Occasionally, having very low levels of oil in your vehicle’s engine can result in reduced engine power. As to why this happens, it’s because the highly-sophisticated vehicles on today’s roads have engines with variable valve timing systems, meaning they rely greatly on proper oil pressure to operate at peak efficiency.

Conclusion On Reduced Engine Power

While you can drive with reduced engine power, you probably realize by now that’s not your best option.

Though it may only be bad spark plugs or a loose wire that’s causing your problems, remember that it could also be a major problem with the ECU or other system.

To find out and get back on the road in the safest manner possible, have your vehicle looked over by a mechanic.

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Hi, I'm the founder of VehicleAnswers.com! Having owned a wide variety of vehicles in my life, I was astounded at how hard it can be to find answers to common automotive questions. Rather than sit idly, I decided to create this website to help others!