XC70 Transmission problem

[AndyL]

I have a 2005 XC70 automatic (triptronic) Volvo with 150000 miles on the clock and it has developed a transmission problem.

From cold the car is fine and it runs up and down the gears smoothly however when it has warmed up especially when decelerating it doesn't seem to know which gear to select and becomes lumpy - even to the point of not selecting a lower gear

Any ideas please - thanks

[MacNoob]

At 150,000 miles have you ever changed transmission fluid? If not, it's well past time. Check sticky for Gibbons method or just drain/refill 3.5L 3 times (driving between changes) to get most of it.

JWS 3309 fluid such as Mobil 3309 or Toyota Type IV only.

[AndyL]

Thanks for the reply - the transmission oil has been changed as recommended and the problem seems to persist.

Bit more information just in. Once the engine is switched off after a few minuets the car runs fine again then the problem returns. A diagnostic check showed up the following codes P0700 and P0800.

My thoughts are that the fault may be electrical - any help is much appreciated - thanks

[JRL]

I can't find any PO800
Anyway, it seems you probably have a bad valvebody solonoid(s)
At this point (high mileage you may as well install a rebuilt valvebody and you may be OK after that.

[AndyL]

I can't find any PO800
Anyway, it seems you probably have a bad valvebody solonoid(s)
At this point (high mileage you may as well install a rebuilt valvebody and you may be OK after that.

Thanks for replying

I had the wrong code - it was P0811 and not P0800. The problem still exists however, since the oil change it seems better.

The car often stands for several days - is it possible something was sticking and its loosening up?

[jda2000]

1/2 quart of seafoam transtune, drive for a couple hundred miles and do a drain and refill again. That should unclog any sticky parts.