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Cat Man
Cat Man, Cat Engine Expert
Category: Medium and Heavy Trucks
Satisfied Customers: 8866
Experience:  I am ASE Master Truck Certified.
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I have a 2003 cat c12 505 hp in a beaver RV. Motor seems to

Customer Question

I have a 2003 cat c12 505 hp in a beaver RV. Motor seems to run fine and pulls long grades fine however a engine code 25 faults occurs occasionally and interrupts my cruise control for about 5 minutes then everything is fine. I checked turbo boost and it holds 24 psi wide open replaced air filter same issues
JA: Thanks. Can you give me any more details about your issue?
Customer: why is code 25 which i believe is turbo boost sensor fault occurring?
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Submitted: 1 year ago.
Category: Medium and Heavy Trucks
Expert:  Cat Man replied 1 year ago.

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

Code 25 indicates a boost pressure circuit fault. I've seen this many times. This code is often caused by a faulty boost pressure sensor. I would consider replacing it first. It's possible for the code to be caused by the wiring harness or ECM but that's rare. Normally when one of these are the problem. The code is active all the time.

I would suspect replacing the boost pressure sensor will cure your problem.

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

Customer: replied 1 year ago.
When observing turbo boost pressure while climbing a grade the turbo boost digital read out doesn't stay constant at max boost pressure it moves up and down usually within 5 psi from 22 to 28 is this normal.
Expert:  Cat Man replied 1 year ago.

No that's not normal if the load and speed is steady. The boost may move 1 psi but should not be moving 5 psi.

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.

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