Despite Nissan claims of Altimas having only 1 transmission mesh screen filter, their is a second transmission fine filter. It is located inside the Cooling Housing and is easily serviceable once you know where it is and parts required. Below is from my original thread on another Altima forum about replacing the fine filter.

Google "nissanclub Two CVT Trans Filters - External Fine and Internal Mesh" to find the original thread. It contains pics and info.

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The filter is easy to change when doing a drain and fill or flush. 4 small bolts to remove cooler filter housing, 1 large bolt for inlet line and 1 small bolt holding inlet line bracket.

These are the parts necessary to change the fine filter. I reused the Cooling Housing o-ring since I needed to get the car put back together and Nissan does not have a part for it and Mitsubishi did not have one in stock.

- Fine Filter - Nissan 31726-1XF00 or Mitsubishi 2824A006
- Gasket/O-Ring for Cooling Filter Housing (Nissan does show the o-ring or filter in parts diagrams. They say it is not serviceable - pathetic!) - Mitsubishi 2920A096
- Crush Washers (return line to Cooling Filter Housing) - Nissan 21626-32U00

- Cooler Filter Housing - Torque bolts to 37 in. lbs.