Your vehicle’s ECM or Engine Control Module (also sometimes called the ECU, Electronic Control Unit) controls several important engine functions. If you are looking to replace your ECM, there are both OEM and aftermarket options to consider.

In this blog, we investigate the differences between both options. And help you decide which one is right for your needs.

OEM Engine Control Modules

• Offer a good balance between performance and economy
• Ensure that vehicle performs to manufacturer’s specifications
• Need no modification to work with your vehicle – aside from reprogramming for immobilizers
• Are the best option for those wanting a replacement for their damaged OEM ECM

The ECM fitted at the factory is designed to meet specific emissions and performance requirements set by the manufacturer. Emissions regulations, warranty requirements, and marketing position will dictate how it manages engine performance.

Most importantly, an OEM ECM will ensure that all the complex systems in your car work as intended. They offer a good balance between performance and economy. The programming parameters are the result of thousands of development hours. This ensures the best long-term performance for your vehicle. And keeps your warranty intact.

Aftermarket Engine Control Modules

• Can change engine settings to suit specific needs
• Are not covered by the manufacturer’s warranty
• May damage other engine components
• May not meet emissions requirements
• Can require custom installation
• Are not the best option if you want to replace your damaged or failing OEM ECM.

An aftermarket ECM is designed to change the basic settings of an OEM control unit. If you are looking to boost your performance, change MPG or modify the power delivery, then an aftermarket ECM is a good option.

Modifying Your ECM:

There are several common methods that can be utilized to modify the function of your ECM:

ECM Remap – This method reprograms the original ECM. It can change crucial settings like boost pressure, throttle responsiveness, and fueling. This can result in noticeable power gains or enhanced fuel economy. But, it can also damage the engine and is not always reversible.

Using An Aftermarket ECM – This is when the stock ECM is replaced with an aftermarket version. It allows for more complete control of the engine’s parameters. But, like a remap, it can damage the engine and is trickier to return to stock if required.

Piggyback ECM – Also called a tuning box, this is an add-on ECU/ECM that modifies the stock ECM signals before they are sent to the engine. They can be unplugged to return the vehicle to its original settings. However, they do not offer the full control that a full remap or standalone ECM provides.

In most cases, simply modifying the ECM may not deliver much of an improvement. To see real gains, you will need to modify the exhaust and intake system too. And remember that any modifications that push an engine above the manufacturer’s design limits can reduce component life. And eventually, cause damage. That is why manufacturers don’t cover any damage caused by aftermarket modifications.

OEM Or Aftermarket?

OEM ECMs are the perfect choice for those looking to keep their car stock and ensure it performs as the manufacturer intended. The warranty is retained, and there is no risk that other engine components will be damaged.

Aftermarket ECMs suit those wanting to change their vehicle’s performance. Changing fueling, boost pressure and responsiveness can improve acceleration and enhance fuel economy. But this will invalidate the warranty and can damage other components over time. They are not a good idea if you just want to replace your damaged OEM ECM.

Original ECMs can be very expensive. But you can save up to 75% off new ECM prices by buying one of our quality used parts.

Tom’s Foreign Auto Parts has been providing quality used OEM parts for over 30-years. We have thousands of quality used OEM ECMs in stock. And offer an industry leading guarantee.

Check out some of our most popular Honda and Infiniti  ECMs. We have thousands of parts in stock for other makes, too. So, if you’ve got questions, get in touch online – we’re happy to help you order the ECM you need today.