A 2002 S80 turned up in an estate sale at a cheap price, so despite all the negatives I've heard about the model (what was Volvo thinking--or was it all Ford's fault?) I decided to take a chance on it.
Factory recommended oil/filter/anti-freeze and major brand premium fuel took care of oil leaks and stinky exhaust. Previous owners had had all the recall items fixed, but I found no record of AT fluid having been changed, so I ordered an oil analysis kit to see what to do--some say changing fluid creates more problems, since none have surfaced with the AT, I'll go slow with that.
The usual front end stuff will get replaced by a trusted local mechanic, but I took on the problems of headlight alignment and leaking WW tank myself. A piece of plastic had broken inside the headlight unit which I patched together restoring full adjustment capability, likely a common problem. UK Volvo customers are told that all WW tanks leak on this model if overfilled, but no way, of course, to know what "overfilled" is!
I marked the point where leakage occurred and rigged a float system I can see at the filler to keep below that point--a lot easier than removing the tank.
Many complain about excessive daylight running lights--the cleanest solution would be to trigger parking lights with ignition "run". Any ideas?

"dealer maintained" is a crock in most areas. They do not use 100% synthetic oil, which is needed to keep the engine from clogging up. They never flush the tranny, even though the process only takes 30-40 minutes and 10 quarts of 3309 ATF.

Does this S80 have AWD, then service the Haldex.

Does this S80 have the 6 cyl or the 5? The 5 cyl is easier on mpg and less maintenance.

Keep $500 aside for DIM repair (instrument cluster) and for possible CEM repair. Both computers do not have a large enough heat sink to keep the resistors from frying. You can help by never turning the cabin blower off, keep it on AUTO or low speed. Let the climate control work its magic, all you need to do is set the temps today and never touch it again.
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My back feels better when I sit in a Volvo seat

Thanks for your reply. The S80 I have was a generic model originally placed in leased/corporate service, T6 w/o turbo.
We use a Smart Car for normal errands, keeping the S80 in the garage for airport trips--picking visitors up, etc. Supposedly when the front end work is done the S80 will last as long as I can legally drive.
I have a 12 volt solar power system, battery storage, to which I plug in the S80s battery to keep it up during long periods of non-use. I sometimes disconnect the negative terminal to rest the car's electrical system and initiate a reboot when putting on the road.
So far it seems to me that the S80 is a wonderful air conditioner on 4 wheels--truly amazing as long as it works. What have you found is the cause of computer problems resulting from turning the AC system off?
Technical issues are always interesting. Best wishes, Dan Townsend

Keeping the battery fully charged is probably the best thing you can do. I park my cars indoors, and they will get plugged into a battery 'maintainer' - sort of a smart trickle charger.

My comment regarding the Climate control blower always on, is to keep the computers in the engine bay cool. Some of the intake air goes through the computer box and air then goes to the cabin. The blower rehostat is also cooled by the air flow. I didn't mean that the AC is always on, but that the blower is never turned off.

Most of the computer problems that are in the dash is due to poor design, allowing them to overheat. If the computer that you are using to read this didn't have a fan, you would also have problems. Heat kills.

Same applies for engines with two turbos, the heat in the engine compartment will cook the wiring. There just isn't enough airflow past the turbos.
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My back feels better when I sit in a Volvo seat

Hi Klaus , Is that right? where are the CPUs mounted? Is there room to add some larger heat sink? Another possibility is that if those CPU's are dying from heat that they forgot, or didn't put enough silicone thermal compound on the heat sink? How come the CPU's get so hot? Are they switching high current loads?
If the CPUs are so pricey, hasn't anyone found the Triacs, diodes or whatever items that crap out?

Bill

The DIM and the CEM are both in the dash area. What Xemodex does is replace the failed diodes, re solder, and add a larger heat sink. The improvements have never failed again.
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My back feels better when I sit in a Volvo seat

AT fluid needs to be changed periodically. If it's burned and discolored flush
it yourself. Search for the write-ups and videos. Avoid power flushes.

I added some LED's for running lights powered from the windshield wiper harness
that has the 12VDC available with the key on. You are right about a large current draw with standard running lights.

Bill

Bill, thanks for your reply. What is the issue about power flushes of transmission fluid? Thanks

The consensus is that the power flushes can damage the transmissions, and it's easy to do yourself, see the videos.