Can anyone help me decide whether I should peel off the silicone gasket maker that I used to seal a leak by the PCV nipple on the intake tube? I used about a tea spoon of it, I believe, not knowing that silicone will kill the Cat. This was about 3000 miles ago, and just now I got a dtc code about Cat inefficiency, which I suspect have to do with my wife filling it with regular 87. Anyway, as a precaution, should I remove it and re-do it with sensor-safe silicone, or is it too late at this point anyway, since all the silicone that could have leached into the system already would have done so? Does anyone know?

 

Here is some good information how a catalytic converter and pre/post cat oxygen sensors operate. Silicone can be a problem but there are other potential reasons for O2 and cat efficiency threshold codes, it's all speculation until someone looks at the pre and post O2 cat sensor signals and other related engine tune items.

http://www.autoshop101.com/forms/h64.pdf

 

Turbo or Non?

 

Tech: It's turbo.

FirstV70: Thanks for the link, it had a lot of helpful information. The check engine light hasn't come back on, so I hope it was just the gas. Still wonder weather I should get that silicone gasket maker off, though. Does anyone know weather silicone would continue to leach out for an extended period, or just the first times being heated up?

 

By the way, FirstV70, I used my scanner and tried to read the O2 sensors, but my scanner only shows sensor 2 (rear). All the other people I've encountered in forums that have tried to read O2 sensor data with their scanners on these Volvos can only see sensor 2, as well. Don't know why that is, but I may have to take it to the dealer to read them both, I don't know.

 

Don't be so sure it was 87 octane gas that caused it. In our '06, the RECOMMENDATION is for 91, but MINIMUM is 87. Since my wife drives it, and shops at Costco, guess what she fills it with? And here in the Midwest, any Costco gas station smells more like a distillery than a gas station as all of the gas is E10/ ethanol blend. In about 20K miles, no indication of 02 sensor or cat troubles. Bad gas, yes, 87 octane, not in my experience, could cause your problem. When I fill it, it gets 92 or 93 octane (we have that here), but most of what it drinks is 87 octane. Costco shopper mentality -- can't stand to spend the extra $$$ on gasoline.

While the cat gets very hot, I'd remove the gasket now and replace it with non-silicone. That stuff, based on experience with other (and not as hot) apps leaches something that smells for a long time.