Cat Converter/02 Sensors

[FlyingVolvo]

Here's another topic from my inquisitive mind!

I've been getting the code for the Cat Converter, P0422, "Main Catalyst Efficiency Below Threshold(Bank 1)" in my 2000 V70XC, 142K miles.

But this is what's strange:

• Got the code and reset it.
• 200 miles later, code came up again, reset it again.
• 700 miles later, I get a California Smog Check done.
• The Smog Check passed and I asked the tech about the results. He said it passed, and passed by a lot. Performing much better than the average car that comes in. Okay...?
• A week later, the code came back on (thankfully after I got my sticker!), reset it again.
• Now over 2000 miles later, the code has come back.

So what gives? Can a Cat be "bad" even though it passed the Smog Check perfectly?

Can a rear O2 sensor problem trigger the code? Both O2 sensors are ORIGINAL. No codes for O2 sensors though. I still get usual the usual mileage, about 12-18 city, 22-30 highway.

On a side note/question, is it unusual for O2 sensors to last 142,000 miles?

[JDS60R]

The normal service life of the O2 sensor is 100,000 miles. After that they are rarely accurate and active enough. The taper off in performance slowly and usually do not set a code until it fails completely in some aspect.

Change them every 100K miles with Bosch direct fit and enjoy.

Matt's link and Amazon seems to be the cheapest route to direct fit Bosch.

[whoa]

I'd guess the front sensor and the cat are fine, because you are getting good performance and good smog numbers. So it's probably a bad rear sensor. Now the rear sensor has no effect on performance---it's only there to throw codes when the cat goes bad---so you could just ignore it or try replacing it with a cheapy.

[FlyingVolvo]

I definitely would like to replace the O2s soon. I know people have complained about replacing them with the wrong ones which is why I'd like to get them from FCP which seems to have the OEM ones. If someone can find those exact ones on Amazon, I'd be more than willing to buy them through the link. I just don't want to get the wrong thing, since I don't have tons o' cash to throw around.

I was pretty sure the O2s had been replaced since my dad had mentioned something about them. So I looked in the service records, twice, saw nothing. Called him up and asked, he said an initial suggestion for the symptoms of a bad MAF had been the O2 sensor, but it was never replaced.

[JDS60R]

Many have the bosch part number stamped on them. I have a little brass brush I use to clean around the sensor to see the numbers.

[FlyingVolvo]

I think this is what I need:

http://www.fcpgroton.com/product-exec/p ... _2000_2007_
and
http://www.fcpgroton.com/product-exec/p ... _1999_2000_

So with those I shouldn't have any issues with the car not liking them?

[jblackburn]

Yeup. Though if you don't need the front one and think it has been changed before, leave it for now and save yourself the money. Your car is only mad at the rear one.

[FlyingVolvo]

I've definitely confirmed neither have ever been replaced, so I think I'll just make it a preventative maintenance deal. Based on the searching I've done, most people say they last usually only 60-100K. So I guess I'm really pushing it a bit. And heck I don't know, maybe they are giving readings that are a bit off causing little things to go wrong in the engine.

Can't hurt to change!

My car is living proof of some guy's signature in this forum (can't remember who): "just think of it as a complete restoration one piece at a time".

[jblackburn]

Mine's 174K old (didn't find it replaced in any of the service records), and looks like a you-know-what to get out

No, wouldn't hurt if you've got the money for it. If you're lucky, your gas mileage will even increase!

I like whoever's signature that is, sounds like my old Honda. It just got to be too much when all the expensive stuff kept breaking.

[FlyingVolvo]

I've heard replacing them is pretty straightforward, but is there a special tool needed? A hollow socket of some sort?