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P0740 and P0743 OBD codes and how I fixed em


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I just bought my Subaru last Saturday (a week ago now) and I've been working through any immediate issues I can easily fix. Two of the four stored OBD codes in the computer were P0740 and P0743. They both relate to the 'torque converter circuitry' somehow. Searching online I found mention of people having a wire severed inside the transmission pan due to pan being dented.

 

Sure enough, my car had a dented transmission pan.

 

http://farm9.staticflickr.com/8340/8274584898_ba67a0afe5_c.jpg

 

 

So I dropped the pan and immediately saw the blue wire that goes to the Duty B solenoid was severed.

 

http://farm9.staticflickr.com/8485/8274585534_db47710203_c.jpg

 

http://farm9.staticflickr.com/8349/8274585154_43d42dd1f5_c.jpg

 

 

The fix was to strip the wire ends, solder them together and use heat shrink tubing on the joint. Soldering a wire that doesn't want to be tinned while ATF is dripping on your and your soldering iron was not really that fun, but it worked.

 

I noticed my transmission pan magnet was quite 'furry' with gray goo.

 

http://farm9.staticflickr.com/8347/8274585800_9c84b53886_z.jpg

 

Hopefully I'm the first person to ever pry the transmission pan off of the car. Is the red goop factory crap from Subaru?

 

I used my heel and a rubber mallet to knock the dent out of the pan and get it back to a normal shape. The longest part of this job was removing the red gasket crap from the transmission and pan. Razor blade + Christmas music...

I used a new rubber gasket and 1194 gray Threebond and it's not leaking.

 

Good news! The 'AT OIL TEMP' light no longer flashes when I start my car. Also, the car shifts better and holds engine power better. I presume gas mileage will increase noticeably as well. I'm not sure how long the previous owner drove the car like this. I don't think it hurt anything. My car is much smoother at idle when sitting at a stop light now as well. I'm happy.

 

I just wanted to share some photos if anyone else ever sees the same fault code and wants to know what wire was cut.

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Had a similar issue, but after dropping pan found that my issue was the dip stick was a little bent and when inserted touched the body of the solenoid and grounded it out.

 

A different dip stick solved the problem, though the problematic one did not seem bent to the eye.

 

O.

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