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Cat Man
Cat Man, Cat Engine Expert
Category: Industrial Equipment
Satisfied Customers: 8621
Experience:  I am ASE Master Certified.
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I have a cat 3126, I replaced the HEPU pump, fixed some

Customer Question

I have a cat 3126, I replaced the HEPU pump , fixed some problems but not all, I still have a intermitten crank and no start , I am getting a code 18 and 39
Submitted: 1 year ago.
Category: Industrial Equipment
Expert:  Cat Man replied 1 year ago.

Thanks for asking your question. I will try and help you out.

Code 18 is defined as injection actuation pressure output fault. This is the two wire circuit that runs from the ECM to the heui pump. Since you have replaced the heui pump. The problem is either in the harness or the ECM is faulty. I would replace the two wire harness. Cat sells a two wire bypass harness. You do not have to replace the entire harness. If the harness is not the problem. It must be the ECM.

Code 39 is defined as an injection actuation pressure problem. This can be caused by the code 18, a bad heui pump, faulty IAP sensor, or a leaking injector.

Please reply back if you need more help or have more questions. I am happy to assist.

Expert:  Cat Man replied 1 year ago.

Hey. I just wanted to see how things were going. Please let me know if you need more help. I am happy to assist. If my information was helpful, please leave a good or higher rating so that I receive credit. Thanks.