I bought my 96 non-turbo 850 with 90,000 mi a year ago, without service records. I replaced the time belt and spongey master cylinder.
On Friday, it died while idling at an intersection. Earlier that day, I had replaced the rear brake pads, and caused some overflow spillage of brake fluid from the master cylinder. A little had leaked on to the electric connectors below the cylinder, perhaps the O2 sensor leads. I took these apart, wiped off the fluid, re-assembled and the car started and ran fine. Until I hit rush hour traffic jams and it died again at idle.
I got to my Volvo dealer. On computer, there's 2 errors. Cyls 1 and 3 are misfiring, and the catalytic converter is blocked, preventing air flow for ignition.
Since I don't have records, the mechanic suspects the spark plugs are bad, and/or a fuel injector is stuck open. Either of these problems explains the misfires. And, eventually leads to destroying the catalyst element with unburnt fuel. The mechanic thinks the brake fluid spillage is not pertinent, just coincidental.
I bought new plugs, cables, cap and rotor and replaced these at the dealer. These were well overdue. The car runs fine since then, but I haven't had any prolonged idle tests.
Should I stop with this? New injectors and catalytic converter are very expensive, especially at the dealer.
He may be right about the cat, because of the strong sulphur smell when the car died - I think this is the catalytic element. But, dealer wants $1,002 for a new cat, plus labor. Understandably, the dealer does not recommend a cheaper after-market alternative, but the mechanic strongly cautioned that I must make sure that the locations of the two O2 sensors are at the exact correct distance along the exhaust system.
Some quick checking online shows aftermarkets cats for under $300, but hard to measure the O2 sensor ports locations. Has this group found a correct OEM product, other than dealer?
I have also seen a $60 (or less) "universal" product, which is just the oval shaped section of the catalytic converter that encloses the catalytic element working part of the exhaust pipe. To install this, you have to torch-cut the old part out of the mid-section of the original pipe, then weld the new part back in its place. I don't have welding shop at home, but this is fairly ordinary for any muffler shop. Does this group have any good or bad experience with this strategy?
Thanks, Pat Q in Dallas/Ft. Worth