Hi,
Two things - a cylinder leakdown test will show up cracked blocks, leaking head gaskets, or a bad valve job.
Similarly, you should also pressure test the cooling circuit to test for leaks.
Get the car back to the dealer so they can use the select monitor to read the error codes causing your CEL.
Rgds,
Alex
[This message has been edited by AlexM_UK (edited June 04, 2001).]