Hello All,

I want to provide you with an update to my "CEL" problem described above indicated my catalytic converter was failing. Based upon my last response, I thought I had "fixed" the problem by tuning up the car (including replacing the spark plugs with Volvo plugs & air filter), having the fuel injectors cleaned, having a fuel cleaner installed, and having a can of B44K fuel cleaner installed.

All was well since the end of August till now, 12/23/20 when the CEL came back on again. According to my mechanic, the CEL is due to the catalytic converter. The code that was given (the exact number I do not know) indicates the catalytic converter is not as efficient as it should be in removing pollutants.

At this juncture, I will be ordering an O2 spacer from iPd, Inc. to see if that fixes the problem. While I was inquiring about the spacer, the representative said the reason why my car is having problems with the catalytic converter is because I have been running the car on 87 grade octane instead of 91 as recommended by the owner's manual. This is sobering news for me. When I purchased this car used with 12,0000 miles on it, and attended an "Owner's Open House" at corporate Volvo's office in Rockleigh, NJ. On hand was a Volvo engineer who said, that although I should run the XC on 91 grade, it would not damage it to use 87 grade. So that is what I did. At 163,000 I burn a valve. 20,000 miles later, I burned another valve. Both times I have the all the valves replaced and the head removed and sent out to a machine shop. These repairs were expensive. 8 years ago, I replaced the catalytic converter with a Volvo unit, when the original catalytic converter was damaged due to collison. Now that catalytic converter is throwing off a code that has triggered the CEL that indicates as stated above, the converter is not as efficient as it should be.

At this juncture, I am wondering if it was a huge mistake on my part not to have been using 91 octane all along. I have two '96 non-turbo 850 wagons, that I run on 87 grade without any valve or catalytic issues. Their owners manuals also recommended 91 octane, but I have never had the issues I have experienced with my '99 XC.

I would like to hear from other XC owners what grade of gasoline do they use? 87 or 91? I realize, switching over to 91 octane may be too late, the damage has been done. But I would still like to hear from other owners on what grade of gasoline they use. I may be too late, but I can always learn. Thanks to all who respond.

Hugh