My father-in-law just had his 2001 Alero 3.4L (3400 SFI) engine rebuilt by a couple of guys and his engine dies when he puts the AC in max. When he asked me to hook up his scan tool to see if I could find anything, I said sure and took a look at his instrument cluster and it was lit up like a Christmas tree! Every single trouble light was lit. I found 9 DTCs: P1189 three times, U1040 three times, U1000 twice, and P0717 once. For the ABS codes listed, I found C1225, C1226, C1236, C1254 (twice), and C1298. Anyone have an idea what has happened? I asked my father-in-law why he doesn't take it back to those two guys and let them take care of it but he said they don't know anything about it. I tried to erase the codes but they came back immediately. Thanks.

The codes should be P1189 Engine oil pressure EOP Switch circuit and Code P0717 is triggered when the transmission'* Input Speed Sensor isn't providing a signal. The U codes are communication error faults. At first it sounded like they didn't properly reconnect the oil sender or tranny sensor wiring properly, the wiring was damaged during the rebuild or possibly they bent some pins at the connectors. But the ABS codes show it'* getting wheel speed sensor faults front and rear at the same time. You know, it'* sure making me wonder if maybe those guys pinched/damaged a wiring harness but I'm not familiar enough with the Alero to know if all those wires are actually in a portion of a harness where they are all right together or if they all share a common connector in a harness or at a firewall or somewhere. Hmmmmmm...

Not too sure what those guys could have messed up, but that is a lot of trouble codes, only time I have heard of that many was from a bad PCM, but I am only speculating here, I have no experience with the Alero'*.

I did change your thread tittle though, that way you can get help easier, and when others do searches for similar problems they will come across this thread.

Knowing the engine was just rebuilt, check over the grounds for loose connections or wires not fastened. the majority of the wiring for the grounds should be where the engine bolts to the transmission. Loose grounds and battery cables can do really funky things.