2001 pathfinder: Is fixing p0744 a do-it-yourself project?

[eriley0731]

My 2001 Pathfinder has about 90K miles on it right now. I've had intermittent transmission problems since May 2005 at about 70K miles. In June 2005 I took it to the dealer. He said I needed some kind of valve and/or solenoid replaced, but that every time he does that he has to replace the transmission within a year, so I should go ahead and have the transmission replaced for $2900. I've put it off for a long time since it's still very driveable, and I'm still having the same intermittent problem.

My MIL has been on for a long time, and I don't know when it first came on. I've been to Autozone with it once or twice to read the code but kept putting off repairs until recently. I don't know exactly what it said on those readings.

I recently bought the Auterra OBD II scanner and got to work. I had the following codes present.p0744 (Improper Lock-up Operation)p0138, p0139 (oxygen sensor, bank 1 sensor 2)p1140 (IVT control position sensor)

This week I successfully fixed the p1140 problem with an $80 part from Autozone and tips from this forum (thanks!). I have the replacement part for the oxygen sensor problem and plan to replace it this weekend. However, the p0744 problem won't be easy. I've got a service manual and I'm looking at the procedure, and it looks intimidating. It may be over my head. Also, I cleared the codes after the p1140 repair, but the other three codes came back.

The p0744 problem seems consistent with the driving symptom I've had for the last 15 months. It's a lurching and hesitation that occurs only in the range of 40-70 MPH, and only intermittently. Pressing the overdrive off button usually changes the symptom, but it can occur even with overdrive off (but I don't know if the p0744 code occurs with overdrive off).

I took it to a transmission place (one I've been happy with before), but he said he didn't think it was even a transmission problem. He suggested an engine tuneup. I haven't done that yet though.

But my more immediate problem now is getting a new inspection sticker (in Texas). I think I can fix the oxygen sensor problem, but I'm worried about the p0744 problem. But at the same time I don't have a lot of confidence in the dealer. I don't want to hear again that I need a new transmission. And my transmission shop is blowing me off. He didn't even charge me to look at it before.

Is there a fix for this p0744 problem that doesn't require a new transmission? Is there a reliable procedure for fixing it? Do I have to be a transmission expert to have any hope to tackle it?

Also, I'm wondering if I can clear my DTC codes with my Auterra and drive around with overdrive off to avoid setting p0744 again, and drive that way long enough for my sensors to read "ready" for the emissions inspection test so that I can pass inspection. Is this a silly idea? Can it work?

Apologies for the long-winded post.

Many thanks in advance for any help.

- eriley

[Q45tech]

Find a shop with BG Fush machine and have a pan drop, filter change, and ATF total replacement after circulation BG Quick Clean [valve body varnish remover] for transmission....................then add 11 ounces LUBEGUARD RED to NEW ATF.

Above done correct should cost <10% of a transmission replacement...........good value IF it extends the replacement by a year.................transmission life with proper maintenance is 7-10 years.

Lack of maintenance is the number 1 reason trannies don't last much beyond 100k in many situations...........whereas with they can go 200k.

[eriley0731]

Thanks for the tip. I forgot to mention that when I took it to the dealer that first time, they upgraded the software on one of the controllers and did a standard transmission service. It helped a little but not a lot.

I'll look into your suggestion. Thanks!

[NISTECH]

Your problem definitly sounds electronic. I work for a nissan dealer and I dont totally agree with your dealers crystal ball diagnosis your trans will fail.

Q45 techs advice is a good start. Althugh they dont call it a filter in the trans , its reffered to as a screen. You could probably do the solonoid replacement yourself but total trans R&R is not really a DIY unless you have experiance pulling one.

Your O2 codes will require a reprogram of the ecm or you could see the failure of another O2 the ecm reprogram stages the amperage applied to the o2 to help burn off any condenstion in the exhust on start up. Thats likely why it failed.

If you takle the solonoids in the trans be sure to follow the service manual closely since you can only remove certain bolts from the valve body to drop it down and gain access to some of the solonoid retainer bolts. Pay close attention to bolt lengths from the valve body as some will be loger or shorter then others. They must be returned to their exact position.