I have a 1984 Fj60 with a 1988 Fj62 fuel injection engine head on it. The donor engine was already desmogged so i put on a desmogged EFI on. I left my catalytic converter on when i first drove it (Because i was lazy) but as soon as i cut it off i got the engine codes 25/26. the exhaust pipe i put in to delete the catalytic converter has a ton of pin holes and it has a bad exhaust leak, could that be the cause of the engine codes firing off? with the research ive done its most likely not the O2 sensors but I dont know where to start really. the O2 sensors are before the exhaust leak so im doubtful it could cause the codes.