Get ready for the story, it's a long one... Forgive me if I don't have exact details, it's my finances vehicle.

He bought a 2001 V70XC with 130,000 mile in September 2011. Shortly after buying the car (3 weeks) the check engine light comes on with the catalytic deficiency code. We had the cat replaced by our local custom exhaust mechanic (mechanic A in this situation), he put in an after market cat and told us Volvo cats are a waste of money. We said "ok, you're the expert, let's do it".

A few weeks later the cat code comes on again. We take the car back to the mechanic and he tells us "something upstream of the cat is going wrong, causing your cat to burn up. Take the car to mechanic B and get the upstream problem fixed, then you will need another cat."

We got to mechanic B and they replaced the fuel filter and a bunch of other crap we later found out from two mechanics has nothing to do with the cat. Mechanic B says "ok, you're good to go, install your new cat now."

We get the second aftermarket cat put on with mechanic A. 10 days later the cat code is on again. We go to mechanic A to complain, he says "it's mechanic B's issue". We go to mechanic B, they have us leave the car with them, they claim they will fix whatever is wrong for free. Mechanic B has the car for 3 weeks and calls us and says "I have no idea what is wrong, the car is running perfectly, you need to take it to the Volvo dealer and see what they can find."

We take the car to th Volvo dealer. They also can find absolutely nothing wrong, O2 sensors are good and everything, software is all up to date. Volvo dealer says their best guess is that it needs a Volvo made cat and maybe that will fix the problem.

Sorry so long... Very complicated! Anyone have any experience with this?? Please help!

 

Hi and welcome to the forum.

Without the error code no one can begin to tell you what's wrong. Get the code and repost.

Your post is fine, more information is better.

 

Hmm, I remember studying this in school. Its a air fuel mixture problem...I believe. I was told when the engine is running very lean and i mean very very lean. it tends to melt the honey cone structure inside the cat convertor. which blows a hole right through the convertor and than the engine light turns on because the convertor is not breaking down the exhaust fumes properly. trying my best to help from what I remember but search up this problem at AA1Car Auto Diagnosis Repair Help best of luck!

 

Could it be Mass air flow sensor related.

 

I always thought it was the opposite, very rich and you get the sulfur smell and a glowing cat that is soon to melt the guts out of the cat.

Are you sure a really lean condition will cause damage ?? If it goes too lean there isn't anything for the metals inside the cat to work with and it should just pass through.


Have they replaced the down stream O2 sensor yet ?? Could just be a bad sensor.

It's always ugly when you trust people and you get stuck between A and B pointing at each other and then Volvo says you need to use our part and that MIGHT fix it, they guess. That aftermarket cat had to be certified by either, or both DOT and EPA to be sold so I doubt there's a problem with it if it's listed as a replacement for your year, model and engine.

Was the second cat replaced for free under warranty ??

Was there any physical damage to the cats that have been replaced so far ??

Do you have the make of cat and part number from the repair order ??

 

My 04 V70 had the catalytic code as well. My local mechanic said don't worry about it unless I wanted to spend $1,200+. I noticed a month or so ago when I was working out of my car in sub-zero temperatures & it basically idled all day that the CEL cleared itself & stayed of for a few days only to come back on & stay on. Could the be some residual carbon somewhere causing the catalytic to become dirty? Seems strange it cleared itself.

 

Today started car in the morning & no CEL. Came on after about 5 miles. On at lunch. Could it be a loose wire or fuse?

 

An overly-hot cat is due to too much unburned fuel in the exhaust (running too rich). Can't imagine how lean flow could hurt a cat, it's just hot nonreactive gases. In fact, most EFI computers will cycle a bit of richness into the exhaust every few seconds to keep the cat hot enough to perform its "exhaust scrubbing" duties.

Generally, the upstream O2 sensor tells the computer if the exhaust is rich, lean or correct so the computer can adjust the mixture accordingly. The downstream O2 sensor merely tells the computer if the cat is working or not, and has no effect on air/fuel ratio.

 

While the engine is still warming up, it's in "open loop" mode and is ignoring readings from the sensors. Once the system is up to temperature, it goes into "closed loop" and starts making adjustments based on readings. The CEL probably comes on when the computer goes into closed loop and realizes there's a problem (or thinks there's a problem due to a bad sensor).

 

Aftermarket Cats versus OEM seems to be a bit controversial when one reads thru' old posts on the issue.
Some have success with them on their Volvo's whereas other people do not.
Its true they are much more affordable but possibly in your case, it is not a good idea to have the aftermarket version.

 

i had the same issue with my 2001 Turbo, it is actually a waste of money to get a whole new cat.
it could be your down and upstream O2 Sensors, they cause the code to go off.
bad O2 Sensors cause the cat code to keep reappearing.
has the check engine light been coming on and off ?