Can A Bad Battery Cause Reduced Engine Power? – How To Check?

Cars, especially those used for a long time, face many problems. The warning light suddenly coming on will make many people worried. So, can a bad battery cause reduced engine power?

To know the exact cause and how to fix it, let’s find out in the article below.

Can A Bad Battery Cause Reduced Engine Power?

Can A Bad Battery Cause Reduced Engine Power?

Car batteries operate on the storage process as a secondary source of electricity. It converts energy into electricity for loads if the generator is not working.

It helps to store and provide power for the starting system of the air conditioning system, electric lock, ECU, etc.

The batteries also protect components from sudden current surges when an engine power mode generation system fails.

It is hard to deny that the battery has a very important role and affects the operation of many other parts of the vehicle. So is it reduced engine power cause?

Yes, but it must be the direct cause. A failed battery cannot provide enough voltage and cannot supply enough water to the starter circuit.

If your vehicle receives poor maintenance, this affects your engine over time. At first, it will probably just be light or two flashes; then, the low engine power can cause driveability issues.

Why Does My Car Say Engine Power Reduced?

After a period of use, the car engine has a state of reduced capacity. Therefore, knowing the cause is extremely important to take measures to deal with it promptly.

Here are the common causes:

TAC System 

TAC (Throttle Actuator Control) is a familiar system on many current car models. It stands out with the ability to control the timing and fuel injection.

If the fuel system or fan clutch fails, it will cause the TAC to behave abnormally, such as the power light suddenly coming on, interrupting fuel delivery to the engine, etc. The result is a reduction in car power.

Spark Plug Problem

Spark plugs can get dusty, soot after a long operation, or because they are not properly maintained.

Ignition from spark plugs with lots of coal dust is not strong enough to ignite fuel and air. Defective spark plugs also cause the spark to weaken.

In addition, the gaps in the spark plug also make it weak and lead to reduced power in the car engine.

Faulty Fuel System

The engine power reduced light will glow when the cap is loose. In addition, the car’s lack of force when accelerating indicates that the fuel filter is faulty. This fuel intake delivery helps the engine burn.

When faulty, acceleration will work poorly, and the vehicle may not start.

These errors are very common for used cars, so it is difficult for used car buyers without experience or careful inspection to detect errors.

ECU or Data Network Problems 

ECU (electronic control unit) is an important part of the “brain” of the vehicle. It is responsible for processing and controlling systems.

When the ECU box has a problem, the engine, airbag, transmission, or any system will not be able to operate normally.

Two main causes of car ECU box failure are overvoltage issues and external factors such as water ingress.

When water enters the ECU box, the component pins will be corrupted, short-circuited, and broken.

Faulty or Damaged Wiring

The high-voltage wire is a component associated with the operation of the spark plug; it has a resistance of about 5000Ω.

After a period of use, the loose power wire will also wear out, affecting the fuel and air mixture inappropriate.

Therefore, a faulty high pressure will reduce the spark plug’s ignition performance.

Faulty Oxygen Sensor

The oxygen sensor is responsible for measuring the amount of residual oxygen in the car engine exhaust gases and transmitting the signal to the ECU.

The ECU will calculate and offer a fuel and air density balanced plan to get the proper combustion process.

When used for a long time, the oxygen sensor will be dirty, bent, broken, and dead.

This makes the signal transmission incorrect, consumes more fuel intake than usual, and causes the engine power light to come on.

Malfunction Mass Air Flow (MAF) Sensor

Sometimes, your car loses power while driving due to a damaged air filter. A car’s combustion uses fuel and air to generate energy, and the air sensor is the first place it comes into contact.

Here, the trap prevents all debris from entering the combustion chamber. If your car has a bad filter, it won’t be able to drive as smoothly as it should.

If this part is too dusty, the air pressure will increase, hence needing a more fuel intake.

How To ByPass Reduced Engine Power

Proper diagnosis “what would cause reduced engine power?” makes it easier to find solutions.

In addition to taking it to the nearest mechanic to get it on time for maintenance, you can also refer to the following repair manual:

Examine Electrical Wiring  

Examine Electrical Wiring

There are many types of power cords, so if used incorrectly, they can lead to damage, faulty wiring, broken wire, faulty cable, fire, or disrupt the fuel economy.

High voltage wire is an important part of the engine; it carries high voltage current from 30,000 to 50,000V to the spark plug.

Due to direct exposure to engine heat and vibration, high-voltage wires can have reduced electrical conductivity and motor power.

Please check the engine to see if they are lame or lose connections to reconnect or replace a new one.

Examine The Throttle Actuator Control System

Examine The Throttle Actuator Control System

There are many causes of throttle position sensor error. The core is worn out; the wire is broken; the IC Hall is damaged, the jack is loose, the signal is positive, etc.

At this point, you should see when the throttle is closed; the IDL contact is connected to the E2 pin; When the car is slightly on the accelerator, open the throttle to 50%, or when it is released, the contacts are in the exact location or not.

Clean Air Filter

Clean Air Filter

The car air filter is very important, so you should clean it for couple of months to keep the engine running. For modern vehicles, it will be easier to disassemble than old versions.

To clean, you can use a vacuum cleaner or a mixture of water and a little detergent.

Don’t forget to use a clean towel to dry it. However, replacing your filter is the best option if it has been severely damaged.

Test Sensors

Bad Oxygen Sensor

To perform an oxygen sensor measurement, you need a quality Volt-Ohm-Multimeter (VOM) meter capable of measuring battery voltage and giving quick and accurate results.

If the VOM reading is too different, you need to give it to an expert mechanic or replace it.

Check ECU


Similar to the sensor system, you need to use a voltage gauge to check if the power supply to the ECU is stable or not. If you find a serious problem, upgrading or replacing is the way you can do it.

Examine Catalytic Converter

A clogged contactor switch is a cause for many car owners to sigh.

To solve it, you need to bring it to a repair shop for regular maintenance or replace it. However, the cost of a new one is quite high.

Can I Drive With Reduced Engine Power?

When everything is under control, it’s not such a dangerous thing. You can still use it, except for some inconvenience when starting and accelerating.

However, in a fail-safe state, this can lead to many serious consequences such as drivability issues, stopping, fire, etc.

You should notice the maintenance schedule to deal with any strange signs promptly.


Above is the answer to the question: can a bad battery cause reduced engine power? The dead battery is not the direct cause of this condition, but it does have an effect.

To keep your vehicle running, you should have a regular maintenance schedule.

Hope this article is useful to you. Thanks for reading.

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