ccrelan

Hi everyone- I was hoping to get your 2 cents worth on a problem I am having. I just bought my father in laws 2000 civic lx. The car has 258,000 miles and has been in the family since new. It runs and drives very nicely. He put 25,000 a year on it for the last 8 years.

Back in the fall, he had a CEL come on and it was for the convertor. We had the cat replaced and tuned the car up at the same time (plugs, cap, and rotor). The convertor was pretty expensive to replace. I believe it was a dealer only part. He was able to get past NY emissions test after the fix. However, the CEL came back on a few days later. The car runs and drives normally. Now that I have the car, I have to pass the CT emissions test and am still getting the code P0420. I used the car all last week and got 34 mpg to the tank of gas. I talked to a friend of mine and he mentioned the second 02 sensor as a possible problem. When I pulled the codes, I also got P1457. From what I have read, this code is unrelated.

Would you guys have any insight into what may be going on? I would think it would be unlikely the cat is toast after a few months of use and the car running normally. It believe it uses a quart of oil every 1000 miles.

Thanks in advance- Cory

Arthas

Its burning oil? It could be fouling up your o2 or even clogging up your cat.

HondaPartsHero

http://www.civicforums.com/forums/22...on-w-pics.html

ccrelan

I am not positive if it is burning the oil or leaking it. Either way, it doesn't sound likely that it would be enough to do in a cat after 4 months. In addition, the CEL came on right after it passed the emissions test in the fall when the cat was brand new. My father in law didn't care because the car ran no differently. My only concern is getting the car to pass the test as well.

Arthas

I was going to recommend the o2 defouler trick but I think OP wants to get to the bottom of the issue first.

ccrelan

Would it be a waste of money to replace the second 02 sensor? They have them very cheap on Rockauto. I am not sure if the brand matters at all, but there are a couple for under $30.

Arthas

Its worth a shot.

P0420 refers to the cat and/or secondary o2. If that doesnt work and you want a cheap fix, go the defouler route.

deving916

iTrader: (2)

OP, the '02 defouler trick' will help you pass inspection.

I bought my car in florida and needed to pass Ny inspection and had the same p0420 code (I didn't even have a cat, i just had some pipe welded straight through).

The 02 defouler trick will move the secondary 02 sensor back a little further.

In my case, the secondary 02 sensor was reading the same as the primary and that will throw the code as well. So, if you do the trick and move the secondary 02 back, it will give a different reading and your CEL will turn off.

Best $5 ever spent

BryanM.

iTrader: (1)

A P0420 is a code that is telling you that the catalytic is (supposedly) bad and
that the secondary 02 sensor is working.

Unless you have a code related to the secondary (bank 2) 02 sensor, I wouldn't
bother replacing the sensor.

EDIT: Also, a solid ground connection is VERY important for proper 02 sensor operation.

ccrelan

I appreciate all the feedback.

I am still confused how the code can come back on right after the cat was replaced? I would go back to the shop where the convertor was replaced before even entertaining the thought of replacing it again. I think it was about $700 to get done. Does about 325 miles to a tank sound about right for a 2000 lx auto? Chasing this problem is particularly frustrating seeing the car runs and drives 100%. It would be much easier to diagnose if the car ran crappy.

kab00m

Has anyone considered an exhaust leak? I'm not talking about the one that blows exhaust out of a blown gasket or crack in the pipe. This would be a leak actually sucking air into the exhaust pipe. Check all related exhaust piping, hardware and/or manifold for any sign of damage/failure. You have to consider all the possibilities. I know you said it burns a quart of oil every 1000 miles. If this was being burnt through the combustion process, anything other that what is supposed to be flowing through a catalytic converter will dramatically shorten a converter's lifespan. Especially un-burnt fuel (for example purposes)

ccrelan

I am going to take the heat shield off the cat tomorrow and check that everything is bolted down tight. I thought I possibly heard a slight exhaust leak at highway speeds this week, but could not see anything obvious looking underneath the car. I will break out the ramps and get a better look underneath tomorrow.

I talked to my father in law tonight. He confirmed that the CEL came back on about two days after the replacement convertor was installed.