Replacement valve body, part P377402, for the Toyota U340E and U341E 4-speed in Corolla, Yaris, Scion xA/xB and Celica, for harsh or erratic shifts.
A Toyota Corolla, Yaris, Scion xA/xB or Celica GT that shifts harsh into 2nd or 3rd, hangs before it engages Drive, flares between gears, or shudders when the torque converter clutch locks up is almost always pointing at the valve body rather than the clutch packs themselves. This is a replacement valve body carrying casting P377402, built for the Aisin U340E and its U341E and U341F variants.
The U340E family is an Aisin AW-built four-speed automatic transaxle, and the valve body is its hydraulic and electronic control center. It routes line pressure through a set of precision-bored passages and spool valves to apply each clutch and band, and on these electronically controlled units it also carries the shift and lockup solenoids the computer uses to time every shift. See the full range of Aisin-built transmission parts we carry if your vehicle uses a different Aisin unit.
Pull the stored codes first. A fluid and filter service plus a solenoid resistance check rules out the cheaper fixes, but once the valve bores themselves wear oval, no amount of cleaning restores them. Transmission Digest's writeup on the related U341E/F lockup code explains how Toyota's own SL solenoid logic sets a shift-related fault independent of a mechanical clutch failure, which is the same pattern that points at this valve body. Before condemning the part, follow our valve body cleaning and inspection guide to rule out a stuck check ball or a clogged filter first.
This valve body carries casting P377402 and is built for the Aisin U340E, U341E and U341F four-speed automatic as used in the 2008-on Corolla 1.8L, 2006-on Yaris 1.5L and 1.6L, 2004-2007 Scion xA and xB 1.5L, and 2000-2005 Celica GT 1.8L. This transaxle family changed solenoid count and valve layout more than once across that production run, so match the casting number and connector style stamped on your old unit against this listing, or send us your VIN, before ordering. If your casting or solenoid count does not match, compare against our remanufactured U340E valve body, which covers a slightly different application range within the same family.
Drain the fluid, drop the pan and pull the filter, then unplug the solenoid connectors and free the internal harness before unbolting the valve body - note the bolt lengths and positions as you go, and lower the unit straight down so the check balls and accumulator springs stay seated in the separator plate. Most references call for Toyota WS fluid in this transaxle family; check the fill-plug tag or your service manual to confirm before refilling, since using the wrong ATF type is a common cause of shift complaints coming right back. Install a new filter and pan gasket at the same time so debris from the old unit does not circulate through the new valve body - if yours is original to the car, pair it with our U340E master rebuild kit instead so the clutch packs and seals get addressed in the same job. Torque the valve body bolts evenly in a crossing pattern, then clear the adaptive memory and drive through several light-throttle shifts so the TCM relearns clutch apply timing against the new valve body.
| Transmission | Toyota / Aisin U340E, U341E, U341F |
| Part number | P377402 |
| Fits | 2008-on Corolla 1.8L, 2006-on Yaris 1.5L/1.6L, 2004-2007 Scion xA/xB 1.5L, 2000-2005 Celica GT 1.8L |
| Drive | FWD |
It routes transmission line pressure through precision bores and spool valves to apply each clutch and band, and on this electronically controlled unit it also carries the shift and lockup solenoids the computer uses to time every shift, so wear inside the bores shows up as bad shift quality rather than a complete failure to move.
Pull the stored codes and check the fluid first. A clean fluid sample with no clutch material and a solenoid resistance check that comes back normal both point at the valve body itself rather than a worn clutch pack or a failed solenoid.
This casting, P377402, is built for the U340E, U341E and U341F as used in the 2008-on Corolla 1.8L, 2006-on Yaris 1.5L/1.6L, 2004-2007 Scion xA/xB, and 2000-2005 Celica GT. Match the casting number and connector style on your old unit before ordering, since this family changed parts more than once.
Most references for the U340E/U341E family point to Toyota WS fluid. Confirm against the fill-plug tag or your service manual before refilling, since the wrong ATF type is a common cause of shift complaints returning after a valve body swap.
Change the filter and fluid in the same job so debris from the old unit does not circulate through the new valve body. If the transmission has run long enough to cook the fluid, a full master rebuild kit addresses the clutch packs and seals along with the valve body.
Clear the TCM's adaptive memory and drive through several light-throttle upshifts and downshifts so it relearns clutch apply timing against the new valve body. Skipping this step is a common reason a good valve body still shifts rough for the first few days.
