My father has a 2006 GS300 with 157k miles. He reported having issues with RPMs, idle, car feeling slugging, etc. I pulled the codes and got the following:

• P2757
• P2714
• P0761
• P0441
• P0455

I don't want to take it to Lexus and pay $130-160 for a dianostic fee, and for them to tell me that the transmission needs to be replaced. I've done some research and several members have had success by simplying doing a fluid drain & fill, and replacing some solenoids.

With that said, I have a few questions:

1. Given the codes I mentioned above, which solenoids should I be replacing? Part numbers would be awesome. From my research, I compiled these, but I am not sure if I need all 3 replaced.
   • 3528030050
   • 3529034010
   • 3521050010
2. When doing a transmission fluid drain and fill, is there a filter to replace or does some "screen" simply need to be cleaned?
3. Should we do a transmission fluid drain and fill first and see if issue goes away? If not, then move to the solenoids? I ask because if we need to do the solenoids, wouldn't we have to do another drain + fill since some (or all; not sure) of the fluid will be lost?
4. Long shot, but does anyone know of a shop in the SoCal area who is familiar with this issue, and can provide a fix?

Update #1:

I bought 4 quarts of Toyota WS transmission fluid and had a shop drain and fill the transmission. The car immediately felt MUCH better even though the CEL was still on. After 30 miles, I cleared the codes and drove for another 100 miles, and the CEL never came back, but it did get stuck in 5th gear once.

The following day, I drove another 50 miles then the symptoms started coming back.. coindentally (or is it?), I was low on gas (40 miles left according to the dash calculator thing). I pulled over and got gas. Shortly after driving after getting gas, the CEL came on and the symptoms were really bad.

I pulled the codes, and I now have:

• P2714
• P0761

I will likely purchase new solenoids, and have them replaced.

 

Yes there is a trans filter in the pan. I would do the drain and fill first since you can not get all the old fluid out anyways maybe 3 qts at a time, trans hold about 10 qts. so you would have to do this about 4 times to see a difference, drain and put in same amount of fresh fluid, run engine and shift thru gears.
Then clear codes and see if the fault returns. Get the evap leak p0455, p0451 taken care of as well need to smoke the system to see if there is any leaks in the fuel system as this can affect engine/ trans performance i.e rpm , idle issues

 

Update #1:

I bought 4 quarts of Toyota WS transmission fluid and had a shop drain and fill the transmission. The car immediately felt MUCH better even though the CEL was still on. After 30 miles, I cleared the codes and drove for another 100 miles, and the CEL never came back, but it did get stuck in 5th gear once.

The following day, I drove another 50 miles then the symptoms started coming back.. coindentally (or is it?), I was low on gas (40 miles left according to the dash calculator thing). I pulled over and got gas. Shortly after driving after getting gas, the CEL came on and the symptoms were really bad.

I pulled the codes, and I now have:

• P2714
• P0761

I will likely purchase new solenoids, and have them replaced.