[MeyersL]

I have an 06 Forester 2.5x thats automatic. It has been having an issue where whenever I come to a stop (at a stoplight or sign etc.) there will be one or two clunks right underneath me. As well as it seems to lag when I start moving again, almost like its breaking up or having trouble getting into gear. I have no idea why this is happening or if this is even the transmission. I have replaced the ignition coil, plugs and wires, alternator, battery, and brakes and rotors all around within the past year or two. Its only got 85k on it, and I'm worried its something severe. I have a check engine light on but it's for the O2 Sensors/Catalytic Converter that I have yet to address, could it maybe be something with that? Thanks for any and all help

 

[sleepstate]

Low fluid?
You need to have the car warmed, running to check the auto trans fluid properly.

Also check (replace) fluid in both front and rear differential.

 

[MeyersL]

I didn't know the car had to be running to check the fluid. Does it have to be in gear or just neutral/park?

 

[sleepstate]

Just warm, in park, idling

 

[sleepstate]

Straight from the factory service manual

NOTE:
The level of ATF varies with fluid temperature. Pay
attention to the fluid temperature when checking
ATF level.
1) Raise the ATF temperature by driving a distance
of 5 to 10 km (3 to 6 miles). Idle the engine to raise
ATF temperature to 70 — 80°C (158 — 176°F)
2) Make sure the vehicle is level.
3) After selecting all positions (P, R, N, D, 3, 2, 1),
set the select lever in “P” range. Measure the ATF
level with the engine idling for one or two minutes.
4) Make sure that ATF level is above the center of
upper and lower marks at HOT side.
NOTE:
When the transmission is hot, the level should be
above the center of upper and lower marks, and
when it is cold, the level should be found below the
center of these two marks.
5) If the ATF level is below the center between upper
and lower marks, add the recommended ATF
until the ATF level is found above the center between
upper and lower marks.

 

[Ironhead]

Here's a post with a TSB explaining some of the normal transmission clunks.

https://www.subaruforester.org/vbulletin/f89/need-conformation-shift-shock-click-noise-358090/#post3739218

Some days as I slow to a stop, it feels like my torque converter (maybe?) waits longer than I'd expect for it to unlock.