I took my 95 mazda mx6 to the mechanic to have a water pump put in. I told him to go thru the car to see if it needs anything else, and to check to see why the engine light comes on at 40 MPH. He had the car for a week and I went to see what the problem was. He said he didn't know how to read the codes because there were 2 plugs. I was thinking that 1 was for the transmission. Anyway when I picked up the car, he said I needed a new computer that he installed. It was a used one. I never had problems with tranny before, bur after getting it home, tranny fluid was leaking alot. When it got to the point where I was using a Qt. every 30 miles, I took the computer out and saw that the letter after the number on it was not the same as the old one. I took it to a tranny shop and they said it was leaking out the overflow valve and 4th gear ratio was not working. They said I needed a new tranny. I know nothing about cars, but I'm wondering if this computer would have something to do with all this. Can anyone tell me if its worth putting the old computer back in and if that would cause this problem? I also have no power going up hills. I had none of these problems before the car went to the shop. I think I have a ford probe tranny.

 

I'm no expert on automatics, but it does seem that your mechanic and what he/she did is the problem.

A '95 will have OBDI, the original "required" (re: litigated) system which is not standardized but unique to the manufacturer. This makes it hard for the average mechanic to read and interpret the codes.

My guess is that he took a stab in the dark, but also was unable to get the correct ECU for the transmission. I think this to be the important step missed. Since ECU's control nearly everything in our cars these days, I could see where that might cause the trans to act funny, causing the fluid pump to overwork and fluid to be forced out of the filler tube, or not allowing the converter to lock-up.

What you are calling fourth gear is actually the torque converter locking up (non-fluid drive) in third gear.

My suggestion: 1) Take it back. 2) Have your mechanic put the OE computer back in and if the one he installed has done further damage to the trans, you may have a case against him.