I'm still getting code 42

[B'SS10]

My 89 s-10 2.5l fuel injected is running much better now since I put a new ignition module and Hall effect switch. The truck started running poorly but no "service engine soon" light came on. Things quickly progressed and on the way home from work one day, I barely made it to the house before the truck stalled.
This is when the "service engine" light came on. I replaced ignition module and hall effect switch. and it runs pretty good but I'm still getting code 42 (EST).
What should I check? Is the ECM the problem or could it be faulty wiring? Whats my next move.

[amac209]

try this link. it explains the situation better than i can.http://www.troublecodes.net/articles...ndrstd42.shtml
good luck