Over this past weekend we drove the 745 1000 miles around New England. It was in the single digits Thursday as we started out and about an hour out the Check Engine light came on. It's done this a few times in recent weeks, but every time I went to check the codes , the light had gone off.
Then I noticed the plummeting gas gauge. We spent the 1000miles only getting 15-17 mpg. I had noticed the mileage had been dropping recntly (to around 23, usually I get 25-27) but chalked it up to the new tires and cold weather, and I knew the plugs and filter needed replacement.
Along the way I checked the code- 121, AMM fault.
So when I got home I switched the AMM from my 744, which has been in the garage with what was supposedly an ECU or injector problem to the 745 (nice having matching cars).
Whoah, the 745 was now running exactly like the 744 had. Well now I knew that it had been the AMM all along in the 744.
Now have the 745 AMM in the 744 and am checking the gas mileage.
Put the 744 AMM in the 745 and it runs as bad as the 744 had been.
This will be a bummer if I have to replace BOTH AMM's!

Still maybe the bad mileage problem is something else, like the FPR or engine temp sensor.

Anyway I'm looking for at least one AMM ending in 016. I think any 89-92 740, 740 turbo and 240 AMM (LH 2.4) will work. Going to try for a used one if the price is reasonable (like $40). Let me know if you have one for sale, otherwise may venture into the depths of snow at the local junkie.