P0421 code

[littlemoule]

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]

factory powertrain warranty ends at 160,000km. I think the catalytic converter is on a shorter 8? year warranty?

[Mitz]

How do I find out degree of degradation? The handheld tool I borrowed doesn’t report that.

Maybe you can find a shop to do temperature measurement on the catalytic converter using an infrared thermometer to assess performance of the cat.

Testing Catalytic Converters

"To test efficiency, Hold the engine speed at 2500 RPM for several minutes to heat up the catalytic converter and allow engine to idle. Using a pyrometer (high temperature thermometer), measure the temperature of the exhaust pipe around 50 mm before and after the catalytic converter. The outlet temperature should be at least 40°C hotter than the inlet temperature. If not, the catalytic converter may be faulty."

Source:
https://www.repcoservice.com/hints-a...ic%20converter.

I don't think my scanner can read the graph. What exactly am I looking for with the graph that can help me identify the problem?
The only thing that comes to mind is a recent Krown Rusting proofing that was done and the light came on shortly after. I'm wondering if Krown rust proofing got into the sensors or something? As well, I am wondering if this scanner will read and plot the graph:

Have you tried using this feature?

So the Check Engine Light code is back. I spoke to two shops and they said they won't take the O2 Sensor out to clean it because the risk of it breaking is high and they suggested to just replace the Catalytic Converter because 9/10 times it's the catalytic converter with this code. Rip off? Thoughts?

Causes of Converter Efficiency loss

Faulty O2 sensors can lead to converter efficiency failure too. One of the things a lot of mechanics neglect to check is probably the easiest thing to check *— the O2 sensor connections. The connector not only is the supply for the voltage and grounds, but the source of the needed air supply to the zirconium sensor. If the connector is full of oil or debris no air can pass down the wire leads to the sensor internally.

Source:
https://www.underhoodservice.com/oxy...he%20converter.

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.

Catalytic Converters do not go bad by themselves, 95% of the time some other issue with the vehicle will destroy the cat and most of the time it is the Oxygen Sensors.

Source:
https://discountconverter.com/cataly...rter-&News=120

[littlemoule]

95% of the time some other issue with the vehicle will destroy the cat and most of the time it is the Oxygen Sensors.

LOL. This makes no sense. A sensor cannot destroy anything other than itself.

[littlemoule]

P.S. Today the check engine light turned off all by itself again.

[Mitz]

LOL. This makes no sense. A sensor cannot destroy anything other than itself.

haha.. LOL too.. I am inclined to believe you read the excerpt ONLY and did not take the time to peruse the whole content of the link provided..

this is the whole paragraph that may be worth considering at least IMHO

"The most important thing to remember about Oxygen Sensors is that they were never meant to last the life of the car! They are wear items and need to be replaced as you would brakes, tires or spark plugs. When Oxygen Sensors reach 80,000 miles plus...change them. Catalytic Converters do not go bad by themselves, 95% of the time some other issue with the vehicle will destroy the cat and most of the time it is the Oxygen Sensors. Even when you have them checked and the tech says they are operating okay...if the mileage is over 80,000 change them. When sensors reach that age they may still be functioning but the signal they send becomes lazy and since they operate in millivolts the slightest signal fluctuation can cause an air/fuel mixture problem and that in turn will take out the cat. If you are in the market for a converter and the vehicle still has the original Oxygen Sensors you should strongly consider their replacement...if not you could be buying another converter 90 days down the road."

anyway it's your car .. just update us when the problem is finally resolved.

[littlemoule]

Well in that context fair enough. I will need some type of a better OBD scan tool to read what the O2 sensors are reporting. O2 sensor is about $400 so I can't really change it as if it's a $10 spark plug. As of right now, check engine light is gone. I might look at the gas mileage, if mileage is good, meh I will just keep driving.

[mohammad]

Well in that context fair enough. I will need some type of a better OBD scan tool to read what the O2 sensors are reporting. O2 sensor is about $400 so I can't really change it as if it's a $10 spark plug. As of right now, check engine light is gone. I might look at the gas mileage, if mileage is good, meh I will just keep driving.

The O2 sensor is $83 cad on Rock auto right now. Also Mitz is probably talking about the pre-catalytic converter upstream O2 sensor. This sensor is used to help determine Air/Fuel ratio so it being inaccurate could cause the engine to run slightly lean/rich which could eat up your catalytic converter over time.

[littlemoule]

As of right now, the CEL is gone. What should I make of this?

[mohammad]

Resume prayer as mentioned in post #34