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Eric Gardner
Eric Gardner, ASE Certified Technician
Category: Car
Satisfied Customers: 228
Experience:  ASE Certified Automotive Technician with a Bachelors Degree in Automotive Technology
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2005 GMC top kick 4500. I am getting a p0642 code and p0670.

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2005 GMC top kick 4500. I am getting a p0642 code and p0670.
The truck will shut down indiscriminately. Sometimes it will restart other times it will not start for hours. Help

Hello. Based on your description of the codes and the vehicle not wanting to start, and the fact that it can be intermittent issue, my experience with these truck can fall into two different issues.

1. The cheapest and easiest fix would be to replace the fuel filter. I have seen this same issue many times and the symptoms are the same. The fuel filter is so dirty that the injectors are not getting the fuel pressure needed to open the injector pintles.

2. This will be a more expensive fix. The glow plug control module on these truck is notorious for going bad. The result is a no start condition, and/or the vehicle dying while being driven.

I am confident that one of these two things will correct the issue at hand.

Eric Gardner and 6 other Car Specialists are ready to help you
Customer: replied 1 year ago.
we have multiple trucks doing this issue. It is definately not he fuel filter. We have changed those multiple times also we do PM religiously and change fuel filter every other oil change. We will try the Glow plug module.
Let me ask you, will a Glow plug module cause the truck to start fine in the morning but if you shut it down it will not start again for an indiscriminate amount of time possibly not for days?? we have an exact truck doing this as well.