Symptoms of a Bad ECM (and Replacement Cost)

Symptoms of a Bad ECM – The car’s brainbox, also referred to as the engine control unit (ECU) or engine control module (ECM) is a vital component that controls the operation of the engine. The brainbox is a component that controls the operations of a car and ensures the drivability of that car.

The brainbox is a major component of the engine, and it ensures all other components of the car work well. A car’s brainbox can control the operation of the engine and even the entire car because of the series of data it receives from the different sensors monitoring different components or units of the car.

Since the brainbox serves as a computer that controls the engine which will in turn power other parts of the vehicle, any problem with it will affect the overall performance of your vehicle. A faulty brainbox will trigger some symptoms that may require urgent attention in your vehicle. 

This article reveals all you need to know about the brainbox of your car and how to diagnose the component when there is a failure.

What is the Engine Control Module (ECM)?

The ECM, ECU, or brainbox in a car is an electronic processor that converts the data it receives from car sensors in different parts to useful information to be able to control the performance of a car.

The brainbox controls everything in your car from the engine to the power steering, doors, HVAC system, transmission system, etc. The brainbox is made up of a chip that runs its software, and it needs the power from the battery to function. 

The brainbox in older cars was designed to control a few essential components. However, in recently manufactured vehicles, the brainbox controls almost all components in the vehicle.

A car’s brainbox is programmed to know the working condition of every car component it controls. Whenever such a component develops a fault, the brainbox notifies the car user to act.

Functions of the Brainbox

As stated earlier, the brainbox controls almost all components of a car, thus it performs a wide range of functions. The major function of the brainbox is to monitor the sensors and generate error codes anytime it receives data from the sensors on the failure of any component. This information will enable a user to have the component checked ASAP! 

Here are other functions of the brainbox.

  • The brainbox monitors the timing of the ignition by controlling the speed of the spark plugs and ensuring the engine delivers the required amount of power.
  • The brainbox ensures the engine is at the right RPM while idling.
  • The brainbox helps to adjust the air-fuel ratio that is delivered into the combustion chamber.
  • The brainbox regulates multiple functions like cruise control, ignition system, transmission system, emission system, charging system, climate control, automatic gear shifting, fuel injection system, engine operation, and lots more.

Symptoms of a Bad ECM 

Just like other car components, a faulty ECM will show some noticeable symptoms. 

Some of such include:

Engine misfiring and stalling

When the brainbox is faulty, your car will misfire and stall, especially while idling.

A faulty brainbox will send wrong information to the engine which can cause a rich air-fuel mixture or lean air-fuel mixture leading to the engine stalling or misfiring.

Check engine light stays on

A faulty brainbox will cause the check engine to illuminate. 

However, other components can cause the check engine light to illuminate, so it is important to scan the ECU to know where the problem is coming from. 

Poor engine performance

One of the key symptoms of a bad ECM is poor engine performance. 

Once the brainbox is faulty, the engine will begin to malfunction. The engine will produce little power, have poor timing, and will affect other functions like acceleration because the combustion unit is not receiving enough fuel or air due to the brainbox’s failure.

Low fuel economy

A faulty brainbox will cause poor fuel mileage. 

This happens because the unit might be sending excess fuel to the internal combustion unit, which will eventually burn off and even cause environmental hazards as a result of increased emissions from the exhaust. 

When the brainbox causes the engine to be rich in fuel, you will notice that your fuel burns off quicker than usual.

Dead engine

Your car’s brainbox can fail and will prevent your engine from starting. When it gets to this point, the engine shuts down completely.

The brainbox overheats

Normally, the brainbox gets a bit heated up due to the mild level of heat from processors, chips, or transistors. 

However, a faulty brainbox can overheat, and an overheating brainbox will cause damage to the component which will in turn affect the functioning of the engine.

What causes a Car’s Brainbox to fail?

Your car’s brainbox can fail due to several reasons.

Corrosion and solenoid damage

A corroded wiring harness or damaged electronic fuel solenoid will lead to the brainbox’s failure. 

The corroded wiring harness will cause voltage problems or electrical surges in the brainbox causing the dashboard to display error codes. 

Sometimes, the solenoid might corrode on its own due to age and exposure to certain elements and will lead to the brainbox’s failure.

Battery, starter, and grounding issues

Replacing your starter with a newer or aftermarket product can damage your car’s brainbox. 

Many recently manufactured starters bypass the voltage regulator which controls the power that gets into the brainbox. A starter without a voltage regulator will cause voltage problems that can eventually damage the brainbox. 

Also, loose grounding can lead to a brainbox’s failure.

Other causes of brainbox failure include bad jumpstart practice, dead cells, physical contact, or accidents.

How to Test and Diagnose a Faulty Brainbox

There are usually some components that should be tested before deciding if the brainbox needs a repair or replacement. 

You can test and diagnose a faulty brainbox in 3 ways. 

Using an OBD-II Scanner

A scan tool like the OBD-II scanner will allow you to pull out codes from the brainbox when connected. 

When the OBD-II scanner displays the codes, you can read the codes to know what the problem may be. 

Some common codes related to brainbox issues include P0600, P0700, and P0606.

Carry out a visual inspection

A visual inspection will enable you to identify if there are broken or corroded components in the brainbox, loose or corroded wiring, damaged battery cells, etc.

Test battery voltage

The voltage of your car battery can let you know if the brainbox is functional or not. If the battery voltage is low, the brainbox will fail to perform its tasks. 

To test the voltage, you will need a multimeter to check the battery when the engine is on and also when you turn it off. A fully charged battery should read 13.7 volts when the engine is on and 12.6 volts when the engine is off. Any reading outside these means your battery needs to be recharged.

The results from the above procedures will enable you to know if your brain box needs repair, replacement, reprogramming, or if you only need to properly charge your car battery.

Cost of Replacing a Faulty Brainbox

As mentioned earlier, the brainbox is one of the most expensive components to replace. It costs between $450 to $1,750 and this depends on the model and make of your car. The brainbox itself costs between $350 to $1,550 while labor can hang between $100 and $200.

Frequently Asked Questions

How long does the brainbox last?

The brainbox is designed to last for up to 100,000 miles or more. However, some driving conditions can reduce the longevity of the brainbox. Keeping to scheduled maintenance and having some routine checks and adjustments done in an auto repair shop will extend the lifespan of your brainbox.

Where is the brainbox located?

The brainbox is a vital and delicate component of a car, as such, it is usually placed in a secured part of the car to prevent contacts that can lead to damage. The location of the brainbox varies depending on your car model and make. Some possible locations of the brainbox in your car include close to the car’s firewall, behind the instrument panel, close to the climate control panel, in the engine compartment, or underneath the dashboard. Since the location varies, it is important to check your service manual to know the exact location of your car.

Is it safe to drive with a bad brainbox?

No! It is not safe and advisable to drive with a bad brainbox. Once you notice problems with the brainbox, it is necessary to take your car to an auto repair shop for repairs. Driving with a faulty brainbox can lead to stalling or engine failure while you’re driving or idling.

Do old model cars have a brainbox?

Yes! Older model vehicles were also designed with a brainbox. However, there is a little disparity between how they performed then and now. The brainbox in older vehicles was made to control a few specific components of a car but in newer vehicles, the brainbox controls almost all components. The brainbox in modern vehicles is more advanced with designated roles.

Can a bad brainbox be repaired?

Yes! In some cases, the brainbox can be repaired or reprogrammed. This however depends on the kind of issue the component has developed. The brainbox is one of the most expensive components to replace in a car, so it is quite fortunate that the component can be repaired. The unit is not one of those components that can be fixed easily at home especially when you don’t have prior knowledge on how to do it, so, you must take your car to an auto repair shop when you start experiencing problems with it.

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