Ok so here is the deal that I need hep/advice on:

About 2 weeks ago start getting a rattling noise from the engine bay. Freaking out thinking that I am in for "That Post" that nobody likes to make.

Dealer pulls it in and says that it is only the cats rattling. PHEW! Then he says it is $1500 to replace them. Ouch. He does not recomend that though because they are required to replace if the car is less then 7 years old and/orunder 70k miles. I qualify so thats cool. Catch is the CEL light needs to go on before he can do that. Been a couple weeks and no light. Sounds like a Diesel engine and hate that it appears that i am driving a car on its last legs.

The question: How can i get that light to come on like right now?

 

pull off one of the o2 sensor from the cat... turn the car on, that should trigger a cel. Put it back on and hopefully will stay on, on the way to the dealer.

 

You rock - will try that immediately.

 

Bill, I had this happen on both of my cats. I didn't have to wait very long - the light came on within a couple of days.

 

Disconnecting the O2 sensor will easily be seen as a sensor failure and NOT a CAT failure. Different code generated for CAT failure than you will get with a bad O2 sensor. Could erase any trust the dealer has in you.

 

yeah was talking about that with some other car guys over lunch and realizing that very fact. Different code entirely and while the service manager and I are quite friendly, do not want to come in with the wrong code. He advised i just drive it really hard and the light should come on eventually while the cat continues to bust apart. Is that my only option?

 

i'm in same boat. driving really hard.

 

How is unscrewing a sensor off the cat gonna cause a sensor failure.... its still connected. it'll show a bad read and throw a cel... if you want it now, this is the only way.... The question is which sensor, before, after the cat, or both.

Driving hard will do it as well or you may have to drive for awhile...

 

The issue is the specific CEL that would come up is that the O2 sensor woudl have failed, not that the CAT was faulty. The advisor specifically said that when it breaks up inside it blocks exit, so perhaps the after-cat sensor would detect that. If this is the sensor that would detect the variation, then is it tied to a single particular error or is it generic? If generic then this approach would work, if it can distinguish between for example a clogged cat or simply a faulty sensor then i run the risk of ticking off the dealer and/or needing to go to a different solution than a new replacement from the dealer.

 

slow -- like through town with 35mph or lower limits and lots of stop signs, and red lights but shutting engine off before fully warmed it up -- which is rare for me -- and then a hour or two later taking car out for a longer drive. Usually during this second outing light will come on.

Another scenario is after driving 30 miles and the last 20 or so miles freeway driving and then leaving freeway and driving through town to my house CEL will come on.

Colder temperature seems to play a role, but really in my car's case the converter is just worn out. That can happen after 203000+ miles.

CEL can't come on if you don't drive car. So drive it. If converter really shot, either worn out, or suffering from mechanical failure, a CEL will be the result.

Sincerely,

Macster.

 

I just had my bank 1 cat replaced for this week for this very reason. Funny, ran hard on the track, no CEL. Drove a 2 hr rally the same day and the CEL came on. My bet is it will come on soon. Mine rattled for about 2 weeks before it came on.

 

The codes for cat failure are usually "bank x catalyst operating below threshold", which is measured by O2 no? I bet backing out the 2nd O2 inline (but still wired and live) would throw a below threshold CEL as suggested by redridge. I just don't want my fingerprints on the O2 when they diagnose, risk/reward not there for me. If I was running out of warranty, I might be a little more cavalier.

 

essentially you are simulating a bad cat condition by doing this... Im glad someone sees my reasoning... the condition was... the OP wanted the cel to light up NOW.

 

I think I am gonna wait nother week of driving at least. I definitely do not want to try and trick my dealer per se - just wanted to know if there was a particluar driving behavior that would trigger the CEL.

 

My dealer covered my Cats at 90K, said warranty was to 100K which, is a Federal law