I've been driving my max for about 2 months with a bad o2 sensor located in the ypipe. I heard that a bad o2 sensor would make the engine run richer. Would it be a good idea to change the sparkplugs or take it to a shop to perform a fuel injection cleaning?

 

What's the point? If the O2 is bad it'll just mess up the stuff again.

 

I've already changed the o2 sensor, just wondering if I should change the plugs because I waited 2 months to change it.

 

In that case probably.Thing is the sensor was probably bad for a LONG time before the code popped up if it did at all. Just get some NGK copper plugs, $2 each, and be done with it.