You mentioned you use Mobil 1. I also use Mobil 1 and have been for years in all of my cars. Do you think there might be a chance that the Mobil 1 is causing the problems?

I thought about changing the oil next time with the Mobil 1 High Mileage formula because they say it breaks down sludge and dirt deposits left in the engine from conventional oils.

My car is at the dealer now but since it has gotten warm out the Check Engine light is not on anymore. Mine only seems to come on when its cold out. I changed the cam actuator valve and all of the oil galleries in that area seemed to be spotless and clean.

The dealer mentioned when they are changing the timing belt they also change the pulley and tensioner and a shaft on the cam? What is the shaft they are talking about?

My estimate is for $800 for a new temp sensor (they think its causing my starting issues) a thermostat and the timing belt and components.

They wanted over $1000 but that was also for all the stupid stuff I do myself like oil and filter changes, tire rotate, brake check etc.

OH, when I bought my new cam actuator valve, the gasket for it had a screen over the oil supply hole and the original didn't. The parts tech at volvo told me they put the screen on to keep dirt from getting in and clogging stuff up. That also makes me think the P0015 might be an oil issue. I am afraid of trying the seafoam in the oil. How long did you leave it in there?? I can't afford to do anything that will damage this car because fixing it costs a ridiculous amount of money.

i, myself, have done the seafoam on all of my vehicles. that's alot of seafoam. anyway, it specifies on the can to leave it for 15 minutes. you might try pouring it into your gastank and let it work through your lines, also. i've never heard of Mobil 1 causing any codes, so i do not think it would be that. the screen for the galley, maybe. but remember, if something did fall in there, hope that it came out and is not in there tearing anything apart.

Regarding Seafoam:

This was my first experience with it. I put in a pint can and told her to just drive around normally and let me know if the 0015 came back. As the story goes - it didn't (and still didn't today). That little 1.9 engine has a lube oil capacity of almost 6 quarts so I guess that the ratio would have been about 12:1 - Seafaom to Mobil 1.

I have to believe (and seem to recall the old rumors) that if you put M1 in an engine that has historically used non-synthectic oil there is a distinct possibility that it will flush the system to a certain degree. Sometimes to the point of seal leakage/failure

Now here is my theory on this:

It (M1) flushes the system due to its inherent properties and in doing this it dislodges and moves some sludge around. However it does not have the ability to completely break up the contaminants and deposit them in the oil filter. So they tend to end up in critical places in the engine (esp. highly engineered ones like your Volvo)

The M1 kind stirred everything up but then let it settle in the dead ends of the rifling passages and casing bores. To accomplish the final step in the process requires a solvent of some type. No oil company in their right mind would sell a lube that had any great degree of solvent in it.

That's where the Seafoam comes in. It apparently is able to get into those low flow areas and move the sludge on it's way to the filter where it can be removed at the next oil/filter change.

I was relucatant to add anything other than motor oil to my crankcase but had heard no horror stories about SF. The 0015 was drivng me nuts and so I thought I would give it a try.

Seems to have done the trick - so far.