At 123k coils failure not unheard of. Plugs should have been replaced at least once. Other than that your shop seems to like to throw parts and codes. If you did not have the Cat codes before than I would look into their work. An air leak could cause those codes as mentioned by Rick and their work m...

Andy: To sum up your shop's latest advice - "the parts are so powerful the system cannot handle it." First - why did they put them in and if this is the case they should take them out and replace with Volvo OEM. Continuing on this lunacy, the coils are designed for the car and should be ex...

Not sure what a tranny clunk is - but in the end of your post you mention hard shifting between 2 and 3. Are these the same? For tranny clunk I would focus on your transmission/motor mounts. For hard shifting, I would focus on your valve body solenoids. You may get lucky and some clean fluid will re...

A CEM needs programming in two cases: 1) if it has no software loaded (brand new) or 2) if the software loaded is not correct for your vehicle (debate is open on loading different software, but consensus is it can be done). If you have a working CEM with a bad connector, you can swap the connector f...

My original thought is the power/battery - you have a parasitic draw. I would focus on the door switch. Then move to the alternator. Then other circuits. Reasoning - you had an issue and new battery appeared to solve the issue. Battery has enough power to handle the parasitic draw. Now the battery h...

I pulled up 2004 S80 AWD 2.5T at an online dealer site and it shows front struts and rear shocks. Both are pretty straight forward to replace - rear being easier. Plenty of write ups. I did them on by 2004 S80, but b/c of your awd concern I double checked. If I recall on the rear one has to take out...

Just had something similar happen to my BMW. I was able to buy a tap of the correct size/pitch and fix the problem. On mine only the first few threads were messed up so after I got them repaired the lug bolt went in and gripped to torque without issue. Most better tire places have the tap on hand or...

Just clean the surface up well and make sure it is flat. The gasket will take care of most "normal" imperfections. I have never used RTV when it wasn't required. Many do it for good measure - that is your call. Just make sure the "squish" does not get into the coolant system.

My prior post was lost. Background - I rebuilt my 4T65E out of car and screwed up by failing to tighten one critical bolt. Result was internal fluid leak - lack of pressure which burned most of my clutches. I decided to try the in car rebuild b/c the critical seals and TC were already replaced. I fo...

I have had good luck with the SeaFoam Tranny additive. I have had good luck with Valvoline Max Life. Others don't like the Max Life as they claim it is too thin. They may be right in their applications. Were it me I would get a gallon of Max Life and put in the Seafoam (1/2 can). Do a drain and fill...