I've just moved to Spain from the UK, and have brought my 2007 XKR with me. It's already becoming a headache. Shortly before leaving the check engine light came on and in a bit of a rush I took it to a mechanoc who replaced the oxygen sensons on bank 2. Literally days before departure the light came back on, my code reader informed me it was the cat system performing below threshold. I assumed maybe the other 2 oxygen sensons were now failing. I can clear the code and the dashboard telltale goes off, and I can go hundreds of miles, but soon enough (days / weeks) it comes back on. So I bit the bullet and armed with Google translate took it to a local mechanic. He's just told me that the catalytic converters need replacing, not in any way forcefully - he even gave me the number of an exhaust specialist in Barcelona who might be able to replace them more cheaply, but for him to do the work would mean Jag parts, €1400 each.

His diagnostic was to use an infra red thermometer reading temps before and after the cats. Sure enough the after cat reading was about the same / lower than the before cat reading. Is this a reliable test that indicates the cat is shot, or are there other possible reasons why the temperature downstream of the cat is not hotter than the inlet temp? Car drives absolutely fine, no stuttering, misfiring, pausing on throttle, nothing. I was sure it would be O2 sensors so am a bit gutted that I've possibly got another big bill to pay.

 

You're lucky your cats have lasted this long. They are manufactured to last eight years under normal use. If the vehicle has had any problems with air or fuel in the past, that could have exacerbated the problem.
There are temporary tricks to getting rid of the faults, check for "O2 SENSOR EXTENDERS" on the interwebz. This won't fix your cats, but you can get by awhile until they fully explode.
There are specialist shops in the US for rebuilding old catalytic converters by cutting the old ones open and installing new media, but I've no clue as to availability in J.O.E..
Your cats WILL get worse over time and mileage. If your car is a keeper, replace them (or fix them) when you can. Do NOT use that temp fix and then sell it. That would be reprehensible.

Also, for further info, only the REAR two sensors are Oxygen Sensors. The front (forward) two sensors are for Air/Fuel Ratio.

 

Stick a camera down the bad cat O2 sensor port. I had the same thing happen to me. The foam that holds the stone in place came loose and was blocking the air and disintegrating. I bought a cheap replacement cat and it is doing fine but if it goes I plan to cut the OEM one open and try and fix this.

 

I did buy a cheap Rock Auto "replacement" cat for my kid's '07 XKR. It was a cheapo-welded together mishmash of parts that I had to work on for an hour to make it fit. I kept his old OEM to eventually have that fixed for slightly more than the crappy Rock Auto one.

 

Yup probably the same one I bought , supposed to be slip fit wasn't, but price was right , little louder than stock. I put on 3000 miles a year so good for me.

 

R.A. on the left, OEM 4.2 on the right.

 

What's the cell count on the R.A Ceejay , looks tiny compared to our OEM brick variety!

 

I've never heard that before. Surely the the forward sensors determine the air/fuel ratio by measuring the oxygen content of the exhaust gases?

Richard

 

I've no idea what the cell count is, whatever is cheapest I'd suppose. I never did scope it before install. It doesn't SOUND any different.

Yes, they use oxygen in the exhaust also to determine Air/Fuel, but the data is used differently in each.

 

The OE ones have two blocks each, forward 600 cell and rearwards 400 cell, I think. Aftermarket are usually just a single 400-600 celll either ceramic or spun metal.

 

extenders aren't foolproof, you're setting yourself up for 2098\2099 issues.

 

..... which is why it's a temporary fix until you can replace the cats, like I already said. My extender has lasted almost a year so far, and I already have a repair shop set up to fix both when the one gets bad again.

 

I tried sensor extenders and they through a million codes , had them removed and went with the cheap cat , so far so good.

 

Which did you use and what was the source CC?

 

We are tslking O2 spacers are we not? If we are I bought 90 degree spacers as straight wouldn't fit. Don't recall where i got them

 

I got the straight one and it did make the sensor hit the transmission while I attempted to install it. I cut down both the sensor side of the extender as well as the threaded side to make it a half-inch shorter. With just a bit of prying the exhaust I got it to get started and thread in. Installed it is clear of all obstructions.

 

No, the cats not the spacers.