IGottaSy
Active member
http://batauto.com/articles/gmmsundrstd42.html
There is more to it but this article digs deep into the "how and why".
I get this code when decelerating. I conclude that:
1. Timing may not be spot on.
2. MAP reads lots of vacuum upon deceleration.
3. Loose or dirty connections.
4. Spark plug wire near EST lead.
Could this mean early stages of blow-by?
It doesn't always set this code. I can see it after a nice long drive at cruising speed. As soon as truck is in motion, engine under load, it clears itself. Looks like more work to do when truck comes back with a new coat of paint next week.
Check this one out...
http://www.fieros.de/en/v6help/code42.html
There is more to it but this article digs deep into the "how and why".
I get this code when decelerating. I conclude that:
1. Timing may not be spot on.
2. MAP reads lots of vacuum upon deceleration.
3. Loose or dirty connections.
4. Spark plug wire near EST lead.
Could this mean early stages of blow-by?
It doesn't always set this code. I can see it after a nice long drive at cruising speed. As soon as truck is in motion, engine under load, it clears itself. Looks like more work to do when truck comes back with a new coat of paint next week.
Check this one out...
http://www.fieros.de/en/v6help/code42.html