Do it yourself, change the ignition coils on your Toyota Corolla manufactured in the year 2006. The procedure is similar for models produced in 2003, 2004, 2005, 2007 and 2008. To do the replacement you will require new ignition coils from your local parts store, a 10 mm socket wrench and perhaps a flat headed screwdriver. The repair process is fairly simple and it will take you about 15 minutes.
At the beginning, after you open the hood of your car, we recommend you to disconnect the negative cable of the battery. This way you will avoid unwanted accidents like shortcuts or computer errors. After that, you will have to detach the engine cover. You can do it by removing the bolts that secure it, using the 10 mm socket wrench. We marked their position with red arrows in the picture below.
After you unscrew the bolts, the cover will just lift off. Then, you will notice the four ignition coils that you have to service. Using the 10 mm socket wrench, loosen up the bolt that secure each coil and disconnect the harnesses (the bolts are marked with red arrows and the harnesses with blue arrows, in the next image). You can remove the cables very easily, by pressing the small safety tabs on their upper side with your fingers or using a flat blade screwdriver where is needed.
In the end, it is all about installing the replacements. You can apply some dielectric grease on the new coils and then insert them into their holes. Secure them with the 10 mm bolts and connect their harnesses. Reinstall the engine cover, reconnect the negative terminal cable on the battery and you are done. This is all you have to do in order to replace the ignition coils on your Toyota Corolla manufactured between the years 2003 and 2008.