Why is the check engine light on?
 

Hi
My protege5 has 90100KM on it & the check engine has turned on, (at 82,000KM I did a tune up = pvc valve, spark plugs, air filter, cleaned injectors, oil & filter change, trans fluid & trans filter change). I've checked the oil & trans fluid & they seem OK, can anyone else suggest what else they think it could be, that would trigger the check engine light?

Thank you

Well, it could be a lot of things...even just a faulty O2 sensor. Does your car have
any symptoms of running differently at all?
Is there anywhere (I'm assuming you're in Canada) who will pull the code at no charge like Autozone or somewhere?

I am a Mazda technician, so I know a thing or two about these cars. Does it have a hesitation upon acceleration? The most common CEL's I've seen with Protege's are intake manifold gasket leaks, dirty/bad MAF sensors, and faulty EGRs. My bet is that it's one of these problems, you'd never know though until you pull a code... find out what the DTC is and I can tell you most likely what the problem is or point you to the TSB to fix it. Good luck.

I took mine in at 90K . Check engine light was on and like t24U stated it was a leaking intake manifold gasket. The car showed no sign of a problem, rode fine, so the leak must be small but enough to set off the light.