Car ECU Flash Reprogramming & Why Reprogram



We all know how cars OS can get bugs, and they need fixing. Well, car creators learned a trick to get over this issue quickly.

According to ECU coding and flashing, ECU of a car had PROM (Program Read-only Memory) chips which have all the important information and data of various calibration and operating systems. But then Flash reprogramming PCM was introduced which gained hugged popularity.

We will be looking into the benefits the flash reprogramming PCM has and what are the negative effects of it.

What is a Flash Reprogramming PCM?

To understand the Flash reprogramming, we need to understand what PCM what is it did. A PCM means a power-train control module which controls different units in a car to have a positive effect on the speed, working and other aspects of the car.

By different units I mean, engine control unit and the transmission control unit. Usually, a PCM controls over 100 factors in a car.

Flash reprogramming means the availability of those options where you can proceed faster and correct anything wrong quickly in a calculated manner.

It also was electronically programmed which ensured that if the system had any sort bug in the system, it could be corrected by electronic configuration.

When we are talking about flash reprogramming, we mean that unlike earlier PROMs that were a limited source of basic PCMs. With flash programming introduction, the PROMs were replaceable which added to the car’s value and worth. Like when it was introduced some 2 decades or more time back by GM motors.

The Reprogramming:

Usually, the reprogramming occurred when you need to fix any problem in the PCM.  There were many reasons for reprogramming. For instance,

  • Engine unit not working properly,
  • Car effectivity is getting lesser,
  • There is a bug in the system,
  • Factory settings are not working properly,
  • The system was not ready when the car was launched.

Many other reasons were also there, but these were the highlighted ones, and they need quick solutions. The auto-engineers worked a wonderful solution. The replaceable PROM Chip which meant that you can replace the old and defaulted chip with a new one with almost old settings.

All you had to do was to remove the old chip and replace it with new. You can reuse the old one when the highlighted issue is cleared off.


It also was easier when you had this type of chip at your disposal because it comes with many benefits. You could easily change the chip and increase the different affecting factors the engine performance. Like

  • More spark advance,
  • Fuel,
  • More speed.

The basic purpose was to increase the power of the engine while you could operate the old way with chips. Flash reprogramming was used to increase the capacity of the PCM. Also, the PCM was easy to be replaced and upgraded with the latest versions when required.

Because of flash reprogramming, little time was wasted when you need the chip or to upgrade it. Also, whenever you want to check on to any unit’s work, it was easier to go through the configuration and read them and learn about them.


The only negative I learned from flash reprogramming was that there were too man flashes. For every model and for every new year, there were new flashes, and it was easy to get irritated with these kinds of things.

With too many changes happening, new flashes were made, and it meant constant new addition and change. Other than this, flash reprogramming is just like the software of a computer. Easy to use and read for engineers good at ECU coding and flashing.