'99 V70XC running issue, seems like a clogged cat, but I don't think it is.

[bronson75]

The car in question has 204,000 on it. The ETS light has been on for many, many miles. The CEL was on so long it burned out. That being said....
At least 3 times in the last month the car will start, idle rough, and it won't rev past 2,000 rpm. If it's driven, it won't exceed 10 mph. It almost seems like c clogged cat (or a major vacuum leak), but then the next time it's started, it will be fine.
I have removed the ETS module and cleaned it, thinking I had a bad joint in the intake/intercooler tubing, but when I put it back together it had the same issue. It sat for a few days, I started it today, and it ran fine.
I suspected a clogged cat, but I don't think that the issue would be intermittent if that was the case.
I'm looking to sell the car ASAP, we recently purchased an '06 XC90, but I would like to fix the problem so I can sell it as a running car.

[FlyingVolvo]

If the ETS light has been on for "many miles", I'm gonna go ahead and take a wild guess that maybe it's the ETS. The ETM is a known issue on 99-00 cars and they almost all go bad. I replaced mine preemptively with a reman from Xemodex and it's been fine for a long time. https://xemodex.com/

Not sure why you suspect a clogged cat when there's clearly an indication of something else going on.

[bronson75]

There is a 4 page thread I started in 2012 pertaining to my ETM issues I'm re-reading right now, hoping to shed some light on the subject. The reason I suspected the cat was a) the symptoms are that of a clogged cat, and b) I got a P0422 Catalyst efficiency code.
https://www.matthewsvolvosite.com/forums ... hp?t=53751

[FlyingVolvo]

That's funny you mention that code, these cars are so very much the same, haha! I get a recurring P0422 code as well. Happens almost exclusively in colder months though.

[abscate]

Your symptoms dont match a clogged cat, but an ETS in limp mode fits perfectly.