P0421 code

[littlemoule]

I like that idea it's free lol. As for Mitz's suggestion there are just a few things about that O2 Sensor:
1. If O2 was a maintenance item like a spark plug, it would have been mentioned in Factory Service Schedule. There is no such mention of that in Schedule.
2. The source provided are mostly off random websites. Not sure about their credibility.
3. Praying is free so I will take that lol. (in this case it's fine a fine approach as vehicle is running fine).

[mohammad]

I like that idea it's free lol. As for Mitz's suggestion there are just a few things about that O2 Sensor:
1. If O2 was a maintenance item like a spark plug, it would have been mentioned in Factory Service Schedule. There is no such mention of that in Schedule.
2. The source provided are mostly off random websites. Not sure about their credibility.
3. Praying is free so I will take that lol. (in this case it's fine a fine approach as vehicle is running fine).

The upstream O2 sensor that helps with air/fuel ratio calculation is probably not a maintenance item because at least in the North American market the car should be able to detect failure in any 1 of the 3 sensors used for calculating Air/Fuel Ratio (AFR) as its reading will drastically differ from what the computer expects when compared to the other 2 sensors. Although we can maybe argue that a slightly inaccurate sensor may cause the vehicle to run slightly rich or lean without tripping the Check Engine Light.

[littlemoule]

Exactly my point. "Slightly" would still be within specs if it doesn't trigger the code. I reckon the Computer is programmed with a lower and upper bound values stored in its table as a reference it checks against. I think the idea of O2 sensor to be maintenance item like a spark plug is a bit stretched unless it was mentioned in the Factory Service Manual which is not the case. I am just not sold on the credibility of the source/links provided in Mitz presentation of the argument. I guess I'm repeating myself.

[mohammad]

Exactly my point. "Slightly" would still be within specs if it doesn't trigger the code. I reckon the Computer is programmed with a lower and upper bound values stored in its table as a reference it checks against. I think the idea of O2 sensor to be maintenance item like a spark plug is a bit stretched unless it was mentioned in the Factory Service Manual which is not the case. I am just not sold on the credibility of the source/links provided in Mitz presentation of the argument. I guess I'm repeating myself.

You are correct, I actually just released a youtube video that shows this reference table which contains the upper and lower bounds at approximately 6:05 in the video: https://youtu.be/TpE9tt_1GTo?t=365

[Wallythacker]

All good points. yea the car drives fine. No misfire. It doesn't look like any shop wants to remove the O2 sensor out just to clean it. Probably concerned about liability. And I don't have any friend who can help do it. I think I will just get the Exhaust system inspected (I know someone who charges minimal fee to do that $10-$20), make sure no leaks and just ignore the Check Engine Light.
Unless Mitsubishi will cover it under warranty. Car has 168000km on it, does this come covered under warranty? I am in Ontario.

Mohammad answered correctly, the emission warranty is 7 years 160km IIRC.

[littlemoule]

You are correct, I actually just released a youtube video that shows this reference table which contains the upper and lower bounds at approximately 6:05 in the video: https://youtu.be/TpE9tt_1GTo?t=365

What kind of a scan tool is that? is that BlueDriver? I wonder if it's going to be a good investment for me to get a scan tool like that for my mirage which can show min/max and live data?

[littlemoule]

Nevermind I'm stupid, it IS bluedriver, second question still stands - at $100 or so is it worth the investment for someone who is not too mechanically inclined (mostly due to mental health reasons).

[mohammad]

Nevermind I'm stupid, it IS bluedriver, second question still stands - at $100 or so is it worth the investment for someone who is not too mechanically inclined (mostly due to mental health reasons).

The answer to your question is discussed in the last 1 minute of my YouTube video

[littlemoule]

Well that says it all. Gonna make sure no leaks in the exhaust and Just save until I can get a new catalytic converter. Seems like O2 Sensors have been ruled out.

[mohammad]

im not sure why you'd spend money on a converter when living in a province with no emissions test.

have you considered a hack to trick the car into thinking the cat is good, he explains exactly your situation at 1:30 in the video: https://www.youtube.com/watch?v=SLXb4fZx4QA