U240E Transmission Problems: 2-3 Flare, Slipping and P0773

U240E Transmission Problems: 2-3 Flare, Slipping and P0773

If you have a Toyota or Lexus with a U240E and it hangs on the 2-3 shift, slips on the way into second, or throws a P0773, the parts counter answer is almost always "replace the solenoid." That fixes a small share of these units. The rest are hydraulic, and the real damage is in the valve body bore, not the solenoid bolted to it. Here is how to tell the difference before you spend the money.

The symptoms that point at a U240E valve body

The U140E/U240E family has a well-documented complaint set. Per the Gears Magazine service article on correcting Toyota U140/U240 shift troubles, the most common issues are "long, drawn-out, or flare 2-3 shifts, or a 2-3 flare with a bindup at the end of the shift," along with "long, drawn-out, slipping 1-2 shifts."

That specific pairing matters. A 2-3 flare that ends in a bind-up is not a worn clutch pack on its own. It is an overlap problem: one element is releasing before the next one takes hold, then both grab at the end. Sonnax lists the same complaint set for its U140E/U240E valve body repairs, and adds harsh upshifts, harsh Reverse, TCC cycling, TCC slip, low cooler flow, and overheating to the list for one specific worn valve.

Understand what SL1 and SL2 actually do

Before you condemn anything, know which solenoid owns which shift. Per the Gears Magazine article:

  • SL1 controls B1 brake apply during the 1-2 shift, and exhausts B1 during the 2-3 upshift.
  • SL2 regulates C2 clutch apply, particularly during the 2-3 shift.

So a 2-3 flare is an SL1-exhaust and SL2-apply event happening at the same time. If either side of that handoff loses pressure control, you get the flare-then-bind signature. That is why a scan tool that only shows you a code number is not enough here.

Diagnosis: do these four things in order

The Gears Magazine procedure is straightforward and it saves teardowns:

  1. Perform the transmission memory reset. The article points to factory bulletin TC002-03 and calls for a memory reset after every rebuild or repair. An adaptive strategy still carrying learned values from a failing unit will mimic a mechanical problem.
  2. Test the solenoids by backprobing the case connector. Expected SL1 readings are 5-6V in first gear, 0V during second, and 5-6V momentarily during the 2-3 shift. Expected SL2 readings are 5-6V in first and second, and 0V in third gear. Readings that track correctly point away from the solenoid and toward hydraulics.
  3. Check the PCM grounds. The article specifies grounds measuring less than 0.1 volts. A lazy ground produces solenoid codes that no new solenoid will cure.
  4. Inspect the valve body for wear or sticking. The article singles out the solenoid modulator valve and the clutch apply control valve, noting both "can wear; always examine them for wearing or sticking, to avoid slipping or binding shifts."

Worth noting on the code itself: P0773 is a Shift Solenoid E electrical fault, and published cause lists include low or contaminated fluid, a dirty filter, damaged wiring or corroded connectors, obstructed fluid passages, and valve body malfunction, not just a failed solenoid. Check the fluid and the connector before anything comes apart.

The two bores that actually cause this

Solenoid modulator valve bore. Per Sonnax, on U140E, U140F, U240E and U241E units the steel OE solenoid modulator valve is prone to side-loading in its bore. That side-loading, combined with repeated oscillation of the valve, prematurely wears the cast aluminum bore and causes shift and TCC concerns. Sonnax kit 57917E-13K addresses it with a hardcoat anodized aluminum valve, a high-grade aluminum sleeve, and a replacement spring that resets regulated pressure to OE specification.

Pressure regulator and boost valve bore. Sonnax describes continuous oscillation of the pressure regulator valve wearing the valve body bore, producing line pressure irregularities and valve instability, while severe wear of the boost valve sleeve allows EPC and Reverse oil leakage. The listed symptoms are insufficient line rise in the drive ranges, excessively high pressures in Reverse, and shift issues. Kit 57917E-08K includes the pressure regulator valve, spring, boost valve, boost sleeve, and boost valve plug, and requires tooling 57917E-TL8.

Both are wear-in-aluminum failures. That is the reason a new solenoid does not fix them: the solenoid can be commanding perfectly while the oil it commands leaks past a worn bore.

The fix, and how far to take it

If the solenoid electrical tests pass and the fluid is clean, you are repairing the valve body. The lowest-effort option is the Sonnax Zip Kit U140E-U241E-ZIP, which per Sonnax seals critical pressure losses in the main line, clutch apply control, and lockup control circuits, plus circuits known to suffer end plug leakage or poor checkball sealing. The kit contains a Lockup Control Plunger Valve Kit, O-Ringed End Plug Kit, two Accumulator Piston Kits, eleven plastic checkballs, a Boost Valve Kit, and a Clutch Apply Control Plunger Valve Kit. Sonnax states no special tools or reaming are required, which puts it within reach of a careful DIYer with the pan off.

If vacuum testing shows the pressure regulator or solenoid modulator bores are worn out, the drop-in kit will not save them. Those need the oversized valve kits above, and 57917E-08K needs its reaming tool, which is a shop job.

U240E shift solenoid kit for Toyota Lexus automatic transmission
Shop shift solenoids for the U240E →

When the solenoid genuinely is the failure, replace it as a set rather than one at a time. A U240E shift solenoid kit gets the linear solenoids replaced together so you are not back in the pan in six months chasing the next one. Browse the rest of the transmission shift solenoids if you need a different unit.

Identify your valve body before you order

This is where U240E jobs go wrong. Per the Sonnax valve body identification guide, the linear solenoids and connectors changed in 2006: the later solenoids are smaller in diameter, the retaining brackets are no longer permanently attached to the solenoids, and the connector shape is different. Separately, whether the valve body has a central lube feed is critical to proper function, and it is identified by the presence or absence of a lube hole on the top plate of the valve body. Sonnax splits its remanufactured units on exactly those two axes: TOY171 for 1999-2005 without central lube feed (FWD models), TOY172 for 1999-2005 with central lube feed (AWD models), TOY174 for 2006-2012 without, and TOY175 for 2006-2012 with.

Check the top plate and the connector shape before you buy anything. A correct part for the wrong half of the split is still the wrong part.

Replace while you are in there

The pan is already off and the fluid is already out, so do not leave these:

  • Filter and pan gasket
  • Both accumulator pistons and their seals (the Zip Kit includes two accumulator piston kits for a reason)
  • Checkballs, if any are scored or flat-spotted
  • Valve body end plugs and their O-rings
  • Solenoid harness connector and case connector O-ring, if the fluid found its way out

If the fluid came out dark and smelled burnt, stop and reconsider scope. Sonnax lists burnt clutches among the complaints caused by pressure loss in these circuits. Once the friction material is gone, a valve body repair only restores the pressure that finished it off. That is when a U240E master rebuild kit is the honest answer.

Cost and effort, realistically

A valve body reseal with a drop-in kit is a pan-down job: fluid, filter, valve body out, kit installed, valve body back in, reset the adaptives. Figure a solid afternoon for a competent DIYer and a few hours of shop labor. Add reaming for the oversized valve kits and it becomes a bench job with dedicated tooling, which is why most people hand that half off. A full rebuild is a unit-out job and a different tier of labor entirely. The diagnostic sequence above is what tells you which of the three you are actually buying.

FAQ

Will replacing the shift solenoid fix my 2-3 flare?
Only if the solenoid fails its electrical test. If SL1 and SL2 track the expected voltages and the grounds are under 0.1V, the pressure loss is hydraulic and a new solenoid changes nothing.

Do I need to reset anything after the repair?
Yes. The Gears Magazine procedure calls for a transmission memory reset after every rebuild or repair, per factory bulletin TC002-03. Skipping it can leave you diagnosing your own repair.

How do I know if my valve body has a central lube feed?
Per Sonnax, look for the presence or absence of the central lube hole on the top plate of the valve body. FWD units are the "without" configuration and AWD units are the "with" configuration in the 1999-2005 and 2006-2012 splits.

Is the U240E related to the U140E?
They share a valve body family. Sonnax lists U140E, U140F, U240E and U241E together for the Zip Kit and both oversized valve kits, which is why the same wear patterns show up across all four. If you have chased a similar flare on another import transaxle, the AW55-50SN 2-3 flare diagnosis follows the same logic.

Sources