It never ends... Code P0731 "Incorrect gear 1 ratio"???? wtf???

New tranny went in, from a 07 4EAT Legacy with 15k on it.

 

Fluid is full. In fact its a little over full since the error could be from not enough fluid.

 

WTF people, i'm totally out of ideas. my registration is almost due to be renewed and i need to pass the OBD2 check in order to renew.

 

Anyone have any ideas?

the tranny must be out of a slightly diffrent model .. where the diffrentials don't have the same gear ratios.. .. this should not affect the obd2 check tho .. its not emissions related.. for time being .. you can turn off the code with open port ..

Connecticut state law doesn't do emissions thru the pipes anymore. They connect it to the OBD2 connector and any CEL is an automatic fail.

 

The tranny came from an 07 2.5i. Mines a 06 2.5i.

you can turn off the code with open port ..

agreed.. just turn it off.. if you don't have an open port cable, see if someone around you does...

wouldn't it make more sense (in the long run) to just flash an '07 rom into your ECU? that way the CEL wouldn't come back.

wouldn't it make more sense (in the long run) to just flash an '07 rom into your ECU? that way the CEL wouldn't come back.

 

I'm gonna have the dealership do that tomorrow. I was reading and reading and reading more about it and it sounds like I have to get the TCU to 'learn' the new transmission. Gonna have the reflash it to a 07. Hopefully that fix's the problem.

what i'm more worried about is different final drive ratios .. the center diff will die if there is a difference..

 

legacy 4eat have 4.11 final drive .. and outbacks have 4.44 in 2005 model year .. could be the problem .. or simply the first gear is a diffrent ratio but i think that is less likely ..

1&2 would be the same ratio. I do believe that the 4eat from a legacy is 4.11 throughout - 05-09. I know that the LGT changed to 3.90 in 07 (not 100% confident as i dont have a LGT but i believe thats what i read)

 

Outbacks are a whole nother kinda beast. Used car-part.com as my reference and to help me locate/purchase the tranny.

well .. have you tryed disconnecting the battery .. and see how long it takes for the light to coem back on ? maybe jsut disconnect it jsut before you go in for the test ..

Yup. Even tried disconnecting the TCM for a few minutes etc. My understanding now is that it has 3 modes, 2 of which are only able to be accessed via a dealer Snapon MT2500 or the SSM. One of those modes is a long term memory mode.

 

Thank god for facebook. my post "Check engine light from the transmission swap = automatically failing emissions = tomorrow i have to go to the dealership and have them reflash my ECU and TCU = more $$" saved me. one of my friends posted he has the MT2500 and all the kits to go w/ it and actually has never used it so he'll be happy to give it a shot. He's getting a 30 rack for sure. hahaha.