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Cat Man
Cat Man, Cat Engine Expert
Category: Medium and Heavy Trucks
Satisfied Customers: 8621
Experience:  I am ASE Master Truck Certified.
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I have 655-7 code on an 09 c7, i changed injector,

Customer Question

i have 655-7 code on an 09 c7
JA: Thanks. Can you give me any more details about your issue?
Customer: i changed injector, everything running smooth did all tests engine not missing. cant get that code to go away i did the fuel verification test
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Submitted: 12 months ago.
Category: Medium and Heavy Trucks
Expert:  Cat Man replied 12 months ago.
Thanks for asking your question. I will try and help you out.
Normally the -7 codes are caused by a faulty injector. But when they are not, the next most likely cause is a faulty injector harness. I would consider replacing it next. Whenever I find the -7 code still active after replacing the injector. I then find replacing the injector harness next corrects the problem.
One more thing. Make sure there is a spray of oil coming from the rocker arms and landing on the injector. If there is not, the injector will overheat and cause a -7.
Please reply back if you need more help or have more questions. I am happy to assist.
Customer: replied 12 months ago.
If the harness is bad wouldnt it give me an injector miss? I am not getting any misses. Its all smooth
Expert:  Cat Man replied 12 months ago.
No not necessarily. That would only happen if the wire in the harness was completely broken or shorted. If it just damaged or missing cooper strands. It would up the amperage and cause a -7. A -7 code is set by pulling higher than normal amperage on this engine.
Please reply back if you need more help or have more questions. I am happy to assist.
Customer: replied 12 months ago.
Ok, so you think first step is to change harness? And if thats not problem what else might it be?
Expert:  Cat Man replied 12 months ago.
The harness would be next. I've seen many harness under the valve cover cause this.
When it's not the harness hnder the valve cover. All that's left to cause this is the external harness or ECM. Over never seen an ECM cause a -7. Possible but not likely.
Expert:  Cat Man replied 11 months 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.
Customer: replied 11 months ago.
I changed the injector harness. Still have check engine light. Is there a test on ET that i should run that would take it off?
Expert:  Cat Man replied 11 months ago.
Thanks for the information.
Not for a -7 code. The injector solenoid test is the only et test but it's for -3 and -4 codes. I've never seen an ECM cause a -7 code. It's possible but just very rare.
Customer: replied 11 months ago.
what else can i do?
Expert:  Cat Man replied 11 months ago.
The best thing to do that would rule out the ECM would be to install a known good ECM. Unfortunately most folks do not have a spare one to use. But that's the best way. If another ECM does not help, you'll know there must be a problem with the new injector or either the harness under the valve cover or external harness.
Please reply back if you need more help or have more questions. I am happy to assist.
Customer: replied 11 months ago.
Replaced the injector harness already
Expert:  Cat Man replied 11 months ago.
Thanks for the information. It could be the external harness if it has not been replaced.

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