a cracked engine coolant temp. sensor was causing my problem @ 137,000 miles . service bulletin#01-T-07 (Jan.7 , 2003 ) describes
the problem of hard start , erratic idle , etc. and recommends a new
design sensor P/N 21025106 be installed on 1991 -2001 Saturn S-series
vehicles . I put teflon pipe dope on the threads of the new sensor and
removed the old sensor with a 13 mm deep socket . I quickly stuck my
finger over the hole to stop the coolant from draining and put the socket
on the new sensor and quickly installed it . only lost a small amount of
coolant . plugged the wiring connection back up and it now runs good
again . the old sensor had a visible crack . I hope this helps others keep
their cars running. COST OF THE NEW SENSOR $20.77 @ GM DEALER

 

Thanks for the head's-up on the Service Bulletin and the part no. change for the older "S" vehicles