I would just like some ideas for why my check engine light came on in my car. I have a 2006 Mazda 3, 5 speed with 91,000 miles on it. It isn't making any unusual noises, the oil change is up to date and all of the different fuels are at appropriate levels. The check engine light just popped on this weekend while driving about 65 miles an hour on the hwy and it won't go off.

SOURCE: mazda cx7 engine noise

Does the engine have hydraulic lifters? If so air can get into the chamber under the lifter and cause lifter noise.

Diagnosis and repair requires removing the Valve Cover. A fairly easy job for your local shop.

SOURCE: Loss of power and acceleration on Mazda 6 Turbo diesel 2003

I'm assuming that that smoke was more previlant while going uphill because that's when the turbo would be really spolling up to max psi. I would guess that if you really got on the gas hard and got the turbo going even on a flat surface, that you would notice the smoke too. The loss of power and the white/grey smoke are tell tale signs that your turbo is bad or starting to fail. Good luck!

SOURCE: check engine light mazda protege 94 lx

Keep it under 65mph!
Go to the nearest auto parts store and ask them to check it with a code reader. Advanced Auto Parts will usually do this for free!

SOURCE: engine seized no oil did not get check oil or check engine light

The oil pressure warning light only comes on when oil pressure drops below 4psi at this moment there is no oil in the engine most often it does not get to this point because oil, water etc is checked every week. It could be your engine was using oil which would point to an engine fault.

SOURCE: Mazda Miata 2002 Check Engine Light

Your vehicle’s computer system has self-testing capability. When the computer senses that there is a problem with some of the components it stores the correspondent trouble code(s) in its memory and lights up the "Check Engine" or "Service Engine Soon" light to tell you that there is a problem and you will need to have the car diagnosed and repaired. Most of the time this is not fluid level related. Take it to a service center you trust and they can tell you what the solution is.