I have a 2001 Mazda MPV. The van currently has 151.000 miles and has served me well. Recently it started running rough and the Engine Light came on. It shows an error or misfire on cylinder 6 and a O2 sensor. I put new plug wires on about 4 months ago. Should I start with new plugs and see if this helps? Also it has a sucking sound coming from under the intake. Any idea what that could be? I have heard some say that is normal for a mazda and other say I have a definite vaccum leak. Any ideas are appreciated.

 

Changed the #6 plug wire. Car in running tremendously better. Check engine light is still flashing. Will I have to get it reset and another scan done?

 

If you have a vacuum leak it will cause the vehicle to think its running to lean and it will throw up an O2 sensor fault , it sounds to me like you have an air leak . Possible Inlet manifold gaskets or inlet air leak .