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Mon Mar 06 2023

Pros and Cons of Replacing vs Repairing an ECU

Did you know that around 92% of people in the United States own at least one vehicle? Vehicles are very convenient and they can bring you anywhere you need to go. Most modern cars function with an engine control unit.

This is a small computer inside your vehicle that controls your engine. The problem is that this unit may break down one day. This would make it impossible for your engine to run properly.

Your engine might not start at all if the unit is severely damaged. But should you replace or repair your engine control unit (ECU)? What are the pros and cons of each option?

How can you find the best option for you? Keep reading and learn more about what you should consider when choosing.

What You Need to Know About an Engine Control Unit

Many people refer to the engine control unit as the "brain" of the engine. ECUs are relatively modern. Older cars do not have them because they did not have the computing technology we have today.

Today, almost every car has an ECU. The main reason ECUs are in modern cars is to reduce the emissions of modern engines. The ECU receives signals from all the sensors in the vehicle and delivers output signals that enable the engine to function in the most efficient way possible.

The engine control unit may sometimes also be referred to as an engine computer, PCM, DME, or ECM. All of these terms are interchangeable as they refer to the same device. You will often find an ECU in advanced and luxurious cars like BMWs, Mercedes, and so on.

The ECU manages the operation of an internal combustion engine in your car. It receives information from sensors such as the oxygen sensor, throttle position sensor, and crankshaft position sensor. The ECU converts those signals to outputs that intern control the fuel injectors, ignition system, and more.

Without these processes, it would be impossible for the engine to run.

All the engine systems and sensors have to work at very precise times. If either system starts functioning at the wrong time, the engine won't work properly.

It can effortlessly control these engine systems and make sure that everything goes smoothly. In the past, all of these functions were done mechanically inside the engine. But an ECU does more than control the engine's power delivery.

It also functions as a safety system to protect the engine. If it detects any systems that are out of range it will put the engine in a state of reduced performance. This is known as limp mode. It is a function that reduced the performance of the engine to prevent engine damage while allowing the driver to still drive home.

Why ECUs fail

The problem with ECUs is that they're not invincible. While they may be very advanced and may last a long time, they will eventually start to suffer from various problems. There are several reasons why an Engine Control Unit (ECU) may fail.

If one of the sensors that the ECU receives inputs or outputs from fails, it can create a short circuit. Those sensors are connected to the ECU which can then short sensitive electronic components within the ECU. If the electronic circuit within the EUC is damaged, it won't be possible to read or send information to the sensors that control the engine.

The ECU's internal software may also be damaged or corrupted. This may happen if the ECU is accidentally coded with incorrect software or updated with incompatible software versions.

If the ECU does fail, it will then be necessary to replace or repair the unit. But which is the better option?

The Pros and Cons of Replacing Your ECU

Suppose that your ECU has failed. It can no longer run your engine. You might have tried fixing it, but to no avail.

You might bring it to car repair professionals and they couldn't fix it either. You have the option to go to the original manufacturer to replace the control unit. This can often be very costly. Due to the recent chip shortages, it can also take a while to find and order a replacement ECU from the dealer.

An alternative to the dealer replacement ECU is to purchase a refurbished second-hand ECU. Refurbished replacement ECUs can be substantially cheaper than a new replacement ECU from the dealer. Professionals can help you choose the right second-hand ECU for your engine. This ensures that the ECU will function correctly once it is installed. This will only work if you go to a shop that specially deals with ECUs. Most ECUs have to be coded to the vehicle's VIN number with the correct engine software to match the exact engine that was fitted in the vehicle. Without matching the correct software in the ECU to the vehicle's immobilizer, the vehicle will simply not start. That is one of the main reasons why you shouldn't buy a second-hand ECU from a scrap yard.

Scrapyard ECUs are not coded to your vehicle's VIN number and will not match your vehicle's immobilizer systems. In some vehicles fitting an ECU that has not been coded to your vehicle can lead to your cluster displaying much higher engine millage.

It is very important to take professional advice when replacing your ECU. The ECUs are complex devices with specialized coding. Fitting the wrong ECU into the vehicle can have serious consequences.

The Cost of Replacing an ECU

An OEM replacement ECU might cost you between $1,000 and $3,000. More luxurious cars will have more expensive ECUs. Refurbished replacement ECUs can cost between $500 and $1500 with coding.

One of the most important steps to take before fitting a replacement ECU is to have your ECU tested. The ECUs receives and send signals to a variety of sensor. All these intricate circuits make it very difficult to correctly determine if ECU is actually faulty before replacing it. In a lot of cases, the ECU is replaced due to incorrect diagnostics only to sit with exactly the same problem after replacing the ECU. Having your ECU tested before replacing it, is one of the best steps to take to save money.

The Pros and Cons of Repairing the ECU

There is a fine line between needing to replace or repair an ECU. If your ECU is water damaged, you likely have to replace it. But if your ECU is still somewhat working, a replacement might not be necessary.

You can instead take it to the professionals and see if they can repair it. An ECU may have a variety of problems that can be fixed. The biggest tell-tale sign of a failed ECU is engine limp mode, engine nonstart condition, and no communication with the ECU.

But this does not mean that it is time to throw out your ECU and get a new one. You can instead take it to a company that specializes in ECU testing and see what's wrong.

What You Need to Know

The biggest benefit of repairing the ECU is the time required for a repair is 1-2 days. It is also cost-saving.

This is because the ECU will be the same. This is not as with a new ECU which needs to be coded to fit the engine. A simple benefit like this can save you a lot of time and money.

Another important benefit is that repairing an ECU is much cheaper than replacing one. The repair costs range between $200 and $600. This is a great way to save money while keeping your car's engine in good shape.

Cheaper cars might have more affordable repair costs too. The professionals will do all the heavy lifting as they find out what the root of the problem is. Once they find the problem, they should fix it the same day.

Your engine should then be up and running again like new. But if the professionals tell you that the ECU has to be replaced, there's not much you can do. Certain problems can't be fixed. If the ECU needs to be replaced, you have the option between a refurbished replacement or a new OEM ECU.

Making the Right Decision for Your Vehicle

It is important to understand whether you need to repair or replace your ECU. The ECU is the brain of your engine. If it doesn't work, the rest of your car isn't going to work.

ECUs may stop working for a variety of reasons, but it usually starts with failed sensors or corrupt software. The best thing you can do is send the ECU for testing. This prevents the ECU's problems from being incorrectly diagnosed.

This is because ECU professionals can tell what's wrong with your ECU. They can also tell you what the best course of action is. If they find that there is a minor problem with the ECU, they can repair it and send you on your way. If it requires a replacement, they can offer you a refurbished replacement that is 100% plug-and-play.

It's important to choose a company that has experience with fixing, testing, and replacing ECUs.

What to Know

Get your ECU tested to be sure it is actually faulty before embarking on costly repairs. Testing can determine whether you should repair or replace the device. It is important to send the unit to the right professionals too.

Otherwise, they might not repair it properly.

The downside of replacing an ECU is that it costs more money and requires programming.

You can instead hire professionals to do it for you. This is important because most people don't know anything about coding engine control units. Doing it improperly could make the unit run incorrectly.

But when a professional does it, you don't have to do any of the heavy lifting. You can instead use the car as normal once that process is done.

Your Engine Control Unit Options

The engine control unit is an essential part of your engine. If it starts having problems, your car might not run as it's supposed to. You will then have to get the unit tested to see if it needs to be repaired or replaced.

Professionals can help you make the right decision. To learn more about it, check out our services.

Mail in automotive electronic repair services 

The ECU Pro offers an affordable mail-in repair service for automotive electronics. To have your unit repaired, simply remove the part and mail it to us. Our professional team will either test, repair, or clone your unit. 

Our team has over 30 years experience in automotive electronic repairs. We specialize in German vehicles such as BMW, Mercedes and Mini. Our main focus is engine control unit repairs ( ECU, PCM or DME). Our state of the art facility has over 30 test vehicles to ensure that all parts are tested in actual vehicles before being returned to our clients.

    Most of the services we provide is plug and play and doesn't require any additional coding. 

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