Just replaced the motor in a 2003 Outback and now it seems the trans wants to slip or not build up adequate pressure. Before the engine swap the trans worked great. Wondering if I missed something?


Asked by DesertCloud Nov 09, 2015 at 07:40 AM about the 2003 Subaru Outback Limited

Question type: Maintenance & Repair

I replaced the aging motor (193k miles) with one that had less than 50k. Now
the trans feels like it won't build adequate pressure. The trans temp light
flashes. It just doesn't want to really get up and go. The tranny worked great
before the engine swap. I'm racking my brain to figure out what I missed but I
can't find anything.

8 Answers


Recheck (and clean?) big harness plugs under windshield. Did you drain and refill ATF at the same time? Or flush the trans (NOT recommended)? Regardless, either your ATF is really dirty, very low (someone forget to refill?), or the trans inner front seal is old and/or cracked, preventing sufficient pressure build-up to engage. So first, check the connectors. Then drain and refill AT with 3.5 qts ATF. Add a bottle of seal conditioner, and drive for a couple of weeks, hoping to expand that old seal. If it doesn't work OR you still have a flashing AT light then get it decoded and see if you've a throttle body failure. If the latter chase a used AT. Given the sudden onset after motor swap I'll bet there's a bad electrical connection or empty (!) AT. Good luck. lemme know what you find. Ern

1 people found this helpful.

Thanks for the info on the connector. Can you describe what these connectors are for.., what is their job in the operation of the trans?. I checked the level of Trans fluid & it is over full by some amount. The guy I got the car from said he did not flush the trans. He only added fluid. Upon driving it, it feels like it's stuck in third gear. Also, manually shiftIng the trans does nothing in the 4 forward gears.., nothing. It goes into reverse perfectly.., plenty of grab but not hard. It's very response in reverse, but like a turtle in forward gears .It feels like it's stuck in third gear. The RPMs never change when shifting manually, nor does the car respond differently. Once you reach 60- 65 MPH, the RPMs are still higher (~3500-3700), indicating that it's not changing gears into D4.


Check fluid on hot idle...or better just drain it and look at it. Pink and clean? Grey or light tan and fairly clear? If either just refill w/ 3.5 qts ATF and bottle of sealer. Black and dirty? Drain and refill TWICE, with a few miles (or months) to distribute evenly. But if nice new fluid and conditioner doesn't work I suspect a bad connection. If all these are clean get a Subie AT scan to see if you just need a throbble body solenoid or something that can be done with the tranny in place. If not, and you're removing the tranny, just install a different good used one...NOT a "rebuilt" one, as they usually aren't successful (the guy in NJ Subaru used even gave up!).

1 people found this helpful.

I reseated the connectors and changed the fluid and added conditioner. No change. Yesterday, after driving it a while then parking it, the trans got stuck in Park. I found the instructions for clearing it in the owners manual. It also says I need to take it to a Subi shop to get something fixed. I'm not sure if the two items are related. I guess my next step is to take it to trans shop and have them check the codes to see what it could be.


Correction: obviously I didn't mean "throbble"! You may need a Selectronic Monitor at a Subie store to fully check codes. Dunno. This may be a weird coincidence of a bad motor AND bad tranny, but I'll bet it's something simple in the wiring. Maybe the ECU and TCU aren't dancing to the same tune anymore?


The Trans pan had been dented in & apparently broken 2 solenoids & cut a wire. I've repaired the brown wire (transfer case soleniod?) and found the Shift Soleniod 1 and the Line Pressure Soleniods bad (did the ohms test). I check continuity on all the wires going up to the connector at the firewall. I'm now looking for used Soleniods in the local area. If not I will order new.

2 people found this helpful.

Ya did it! Congrats! These solenoids are pretty robust unless clogged with back-flushed detritus. Maybe clean and test before replacing if cost an issue. Who/what whacked the pan that hard?! You live off-road?


I think when the guy changed the engine that he jacked the trans up and maybe it slipped off the jack. There's also scratches & gouges in the undercoating along the bottom of the chassis, giving me the impression someone was rough with it, either just before the engine was changed out or as a part of pulling the engine.

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