code 42

[jd87sep]

driving down the road, and i notice my tach fluctuating, bouncing around everywhere. I thought it was weird, but no biggie. Then the tach does it again, and it dies. code 42 is brought up. Now everytime i start the car service engine light comes up, and its code 42. I had a bad fuse and replaced it, other than that I have no idea where to start. any help where to look would be great.

[Morley]

Electronic Spark Timing bypass circuit or EST circuit is grounded or open. A malfunctioning HEI module can cause this code. It would also explain the dead tach.

[jd87sep]

thanks man, after parking it for a few days I discovered it wouldn't start. Replaced the module, systems all go. Much appreciated.

[Morley]

you DID replace it with an AC Delco unit right? If not you'll be replacing it again.

[jd87sep]

Originally Posted by Morley

you DID replace it with an AC Delco unit right? If not you'll be replacing it again.

...uh oh. i used bosch