just wondering, can my buddies snap on computertell me what the issue is with the check engine light?

the engine drives fine it doesnt seem to be in limp home mode or anything...

also, i have been driving for too long w the spare tire wich has alot more tread then the other 3,
will that make the check engine light come on or just the ASR light?

yea i was hoping to get through the summer with the tires that were on it because i got a psuedo fixer upper
(needs front end work) speaking of which...anyone know what would cause the car to feel like it was attempting to drive itself?
Going strait down the road, it almost feels like the steering wheel disengages for a split second and the car goes off to one side,
but not like an alignment pull, but a "there is no steering" pull

almost like the linkage/gears in the stearing box are shot.

any ideas?

p.s. i got the car for the saftey rating (im a stay at home dad) so any less expensive fix is always better...
it was 94 e320 w.240,000 miles w new $1000 transmission computer. for 2000$ so if i drop 2000$ into her ill be ok w that...

thx