1992 525i
Hello, I am having dire engine problems, let me tell you how it started.

First the check engine light comes on once and a while.
Now its on all the time.
Idle is inconsitant
Engine is running hot. the temp guage goes from the middle to the red every 5 minutes.
i smell coolant everywhere.
Heater blows cold.
My question is. How do i check the error codes without paying my dealer 60 dollars to plug a computer to it.
I tried stomping the gas 5 times within 5 seconds and it doesnt do anything.
What else can be wrong?

Thanks,
Jonathan