aaronrules

Agree with this. Before you decide to add it, monitor your temps. If you’re running sub 190, you’re prob fine. If you typically see 210+ on longer drives/interstate runs, you could already have hardening.

We had the solenoids replaced in April 2025 on our 2011 after getting the codes. Zero issues since then until today (about 12,000 miles). It has been driving fine. I cleared the codes. AT205 here I come. I will probably also add the cooler. I...

Genius!

Clear rubber/plastic hose (somebody here will recall the size, I think 5/8) and a funnel. Drop it down under the hood by the exhaust on the passenger side. You need like 8’ of hose. When you put the AT205 in, chase it with an ounce or two of...

As soon as I can cobble together a way to add the AT205 to the transmission without spilling it all over the place I will do this for sure!

Don’t let me understate the performance improvement of AT205. Amazing product. Likely saved this truck from the sale barn. My truck has issues outside of AT205s reach.

Disconnect the battery for like 30 mins and when you reconnect the codes will be gone. AT205 takes about 5 hours of operation before it’s done its full effect. So you can drive around with the codes (or without them) for 5 hours and then if...

Depends on what the underlying issues were and how bad… I didn’t have major issues, metal shavings and had decent fluid intervals, mine appeared to be either electrical, a sensor or likely we thought pressure holding as it did better overfilled...

Did I see where even after adding the AT205 you can’t clear the codes? I’m assuming the lights go away.

About the cruise control... I have a 19 Lux and use the CC a lot. 2 years ago I was hunting in Ontario, Canada in Sunset Country. About as far North as you can go before the roads give out and Float Planes take over. My CC had stopped working...

Agreed! So many things can fall under these codes.

You don't necessarily need symptoms to get the code, if the ECU detects an unexpected speed mismatch (slippage) it'll throw the infamous "solenoid" codes.

No, access from underneath. It’s a 24mm plug passenger side rear of the transmission. About 2/3 of the way to the top of the tranny

All good! Not a bad question. It’s a sealed system, so you put it in the fill plug on the transmission.

So my wife’s GX has all the associated lights and codes but zero symptoms. The thing shifts fine. The only problem is that her cruise control won’t engage, which we can deal with. Anybody else have similar issues? I’m going to add the AT205...

I’m am thrilled that other people are finally trying and getting the same results as I have had for the AT205! I’m not shocked it has worked so well because all my research prior to trying it suggested the rubber O rings had to be the cause of...

Are you accessing it from under the hood?

There’s a fill port further back higher up on the passenger side. I think it’s a 24 mm, maybe a 26, can’t remember.

You guys will have to excuse my idiocy but I’m assuming you are putting the AT205 into the transmission pan? I couldn’t see/find a fill port when I looked yesterday. And yes I feel like an idiot for having to ask this question. 😬 It’s a 2013 GX.