Need Help with a 2000 Mitsubishi Galant V6 repair?

Question

My car got its "service engine soon" light on, and when i took it to Autozone, it was diagnosed with PO141 and PO306 infections, which in normal terms is an Oxygen sensor(downstream) and a Cylinder6 misfire. I have been doing lot of online research to fix these myself. Please could any1 help me in guiding me as to how to get this done. Getting to the 6th cylinder definitely seems to be a tough one and also is it possbile to remove and replace the sensor without the tool..

Answer 1

I would definitely fix the cylinder misfire first. I would start cheap and simple and go from there. Check/replace the spark plug/spark plug wire/cap.

Answer 2

P0141 does not imply immediate replacement of the downstream O2 sensor.  That may be the problem, but it may not - without a proper scan tool you have no way to tell - and they probably won't let you return the O2 sensor if that doesn't fix it.  Your #6 misfire could for example be messing with the sensor.  Fix the misfire first, then worry about the O2 sensor.

To replace the rear bank spark plugs (which need to be replaced every 30k miles IIRC) you need to remove the Upper Intake Plenum so make sure you get a new gasket for that along with your new NGK or Nippondenso Resistor spark plugs.

Answer 3

I'd love to help. I assume you own a scanner, so hook it up and go to live datastream. Monitor the O2 sensors, make sure they are or are not doing what they should. As far as a #6 misfire, it's pretty easy to figure out. First compression check that cylinder, then have a look at the plug for that cylinder, ohm the ignition cables, get a noid light and check injector pulse, you should be able to narrow it down pretty easy as to which item is causing the misfire.