Replaces the internal filter and reseals the pan on the Nissan RE4R01A four-speed automatic in Pathfinder, Xterra, Frontier, D21, Infiniti QX4 and Mazda MPV.
If your older Nissan Pathfinder, Xterra, Frontier, Hardbody pickup or Infiniti QX4 flares between gears, takes a second to engage when cold or whines under load, a fluid and filter service on the four-speed automatic is the first thing to rule out. This kit is the internal strainer and pan gasket for the Nissan RE4R01A family, the rear-drive four-speed that sat behind the VG30, VG33 and VQ35 V6s. It replaces Nissan strainer 31728-41X01, which Nissan superseded to 31728-41X03.
The RE4R01A pulls its fluid from the pan through this strainer into a front pump that supplies the valve body, the clutches and the torque converter. When the screen loads up with clutch material, the pump starves and line pressure drops under load. On this transmission that shows up quickly, because the third and forward clutches are its known weak points and they burn when pressure is low. TransGo's heavy-duty kit instructions for the RE4R01A list debris plugging the filter alongside third and forward clutch burn-up, a leaking inner 3-4 clutch seal and shrunken sealing rings as the common failures, and recommend an auxiliary cooler.
A flare and a slip feel similar but mean different things, and our flare vs slip guide explains how to tell them apart before you buy parts.
Check the fluid level hot on the dipstick, then smell and look at it. Drop the pan and look at the magnet and the bottom of the pan. Fine gray paste is normal. Chunks of friction material or brass mean the clutches or bushings are already damaged, and a filter only buys time. In that case the RE4R01A master rebuild kit is the real repair.
Nissan's parts catalog lists the 31728-41X01 strainer on 1987-1995 Pathfinders with the 3.0L V6 and the replacement 31728-41X03 on 1987-2004 Pathfinders with the 3.0L, 3.3L and 3.5L engines. The listing also names the Xterra, Frontier, D21 and Hardbody pickup, Infiniti QX4, Mazda MPV, 929 and B2600 and Suzuki Equator, all of which used versions of this four-speed. Nissan used several different strainers on this transmission over the years, so hold the new one next to the one you remove and check that the pickup neck and mounting holes match before the pan goes back on.
One fitment trap is important. From 2005 the Pathfinder, Frontier and Xterra moved to the five-speed RE5R05A, which takes a different strainer. If your truck is 2005 or newer with a five-speed automatic, this kit is not the right part; see our RE5R05A parts page and the RE5R05A service guide instead. If you are not sure which transmission you have, send us the year and VIN.
| Fits | Nissan RE4R01A / RL4R01A / RE5R01A four-speed automatic |
| Replaces OEM | 31728-41X01, 31728-41X03 |
| Cross-reference | FRAM FT1138/FT1145, Purolator P1229, WIX 58906, Mazda BV11-19-815 |
| Kit includes | Transmission filter and pan gasket |
| Common applications | Nissan Pathfinder, Xterra, Frontier, D21, Pickup; Infiniti QX4; Mazda MPV, 929, B2600; Suzuki Equator |
| Item weight | 1.05 lb |
| Ships from | USA |
Probably not. Nissan moved the Pathfinder, Frontier and Xterra to the five-speed RE5R05A starting in 2005, and it takes a different strainer. This kit is for the four-speed RE4R01A family. Send us the year and VIN if you are unsure.
Strainer 31728-41X01, which Nissan superseded to 31728-41X03. Nissan used other strainers on this transmission too, so compare the old and new filter before you install the pan.
Nissan Matic-type ATF or a fluid that is rated for it. Check the owner's manual for your year, and set the level hot on the dipstick after the service.
It helps when the slip is caused by a restricted strainer and old fluid. If you find chunks of friction material in the pan, the third or forward clutch is already damaged and the transmission needs a rebuild.
If you tow or wheel at low speed, yes. Heat is a main cause of third clutch burn-up on this transmission, and TransGo recommends an auxiliary cooler with its heavy-duty kit.
