hi Scotty,

My wife's 2012 Mazda 3 Check engine light came on about a month ago. The car has approx. 136,000 km. It is running smooth no rough idle. We have had it to 2 mechanics, one was a Mazda dealer.

The first mechanic said it is a Cylinder misfire P0303 code. He swapped cylinder 3 coil with cylinder 2 coil and reset the Check engine light. A week later the Check light was back on. I went back to him. It was with same code P0303. This time he switched the spark plugs. He did not reset the Check engine light. But on my drive home it turn off. About a week later the check engine light was back on. The mechanic said take it to a dealer they should have more info. on the reason. Dealer diagnosed the problem ( i explained everything other mechanic did). They said service bulletin says to change the oil and filter, and flash the computer.

About a week later Check engine light is back on. I Called the dealer they are saying only thing left is to open up the intake manifold and clean the carbon build up. This will be about 5 hours labour plus some parts. This would be at least $6-700.00. I will pay for the work, but at this point they did not seem certain it would fix the problem. I feel they are just guessing. They also said put some injector cleaner in gas and drive on hwy. I did this too. Check engine light still on.

I have done some research and they say it can be anything from carbon on intake values, fuel injector to vacuum leaks. Any suggestions? If I keep driving it with Check engine light on will there be any damage?

I am in Canada.

thanks for reading my post.

Comments (3)
No. 1-1
Techsus
Techsus

This is yet another endorsement to get a quasi-professional OBDII scan tool that you can use when CEL comes on. Scotty advises BlueDRIVER, which is why I got one. What make-model-year are we dealing w/ here?