Hey all, I've had fun trying to restore my car back up to a proper working condition. Long story short, purchased car at 145k miles, its at about 152k miles right now. I have short drives, but I have done one long distance drive from mid-Texas to mid-Florida. During the drive in to florida, I had determined that my coilpacks needed to be replaced (I had already replaced plugs) after some cyl failures. They adjusted all of that for me, made sure all cyls are firing, all is well...

On the drive home, I was feeling the improvement of having all of my cyls back in working order, except now I'm getting the P0420 code from my OBD2 reader. As I've done a little bit of research on the forum, I've been told to clear the code and see if it comes back.... as sometimes after changing plugs/packs you need to clear the code a few times before it stops throwing.

Well, at this point, after about 7 or 8 clears and its still coming back, I think its safe to say this is a real p0420 code now. My guess is the catalytic converter is shot and I should look to replace. I've heard stuff about replacing the O2 sensors, but I wouldnt be surprised if its actually the CC.

Final note, I've always had sub-par gas mileage and I've also heard that is a sign of a bad catalytic converter.

Thoughts? What am I looking at in terms of servicing this fix?

 

If you have scanner check the temperature of catalyst after 10 miles driving at 45 mph. If it stays below 200 degrees C the converter is not working as it should

 

No scanner, doc. I can definitely say that it happens after about 30 min - 1 hr of driving on the highway, as that is the only way to test it. My daily commute is 12 min to the office and 3 min ride home, so thats not enough to test and the engine is barely warm

However, yesterday I was driving between Austin and Dallas and thats when I got the code again. So it definitely only pops up after prolonged use. Can you recommend anything else, as I dont have the scanner?

 

Infrared thermometer could measure the temperature of the cat or you can get an extension tube for secondary O2 sensor ; if code does not appear after modification, the cat is bad

 

It's "always" been my experience that a p0420 code is indeed a failed catalytic converter. I've always replaced O2 sensors (upstream and downstream) and have never had it fix a p0420 code. Also, every time before the p0420 code, I had misfires first. The culprit... bad coils. Anytime I see a misfire code I get catalytic converter anxiety! I stop driving the car immediately and replace plugs and coils. If the car has over 100/120k on it I do the O2 sensors too.

 

For replacing the o2 sensors, are the upstream and downstream sensors the same? I know there are literally 2 sensors, but I was wondering if I could buy 2x replacement of the same make sensors...?


annnnd edit: I found my answer. Upstream and Downstream sensors. I'm going with Denso off of Amazon.

Upstream:
http://a.co/jdjogdC

Downstream:
http://a.co/2ceh7j5

 

Rock auto has them as well and usually priced right, There delivery is usually very fast..

I had the same issue, ran a can of Seafoam through 3 tanks of fuel and adjusted the valves. No further issues.

Cheers

 

Love Rockauto, I get almost everything through them.

I suppose that a valve adjustment could clear things up, especially if the plugs and coils have been replaced too. If things are out of spec that would contribute to the issue.

 

I have the same P0420 code,but since on my country there is no smog regulation would going with a T1R test pipe do the job or could I just delete the cat?

As a cat converter is expensive (almost $800 for an OEM one)