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Ronnie
Ronnie, ASE Certified Technician
Category: Lincoln
Satisfied Customers: 35305
Experience:  35 years as an automotive tech
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Lincoln Navigator: I had an engine replaced on a 2004 Lincoln

Customer Question

I had an engine replaced on a 2004 Lincoln Navigator just over 1 yr ago. The check engine light came on immediately. The error codes indicate a vacuum leak. I have had it to 3 different service techs over the last year and no one had found it yet. the truck runs fine. Is there an easy way to permanently turn off this light...disconnect it?
Submitted: 1 year ago.
Category: Lincoln
Expert:  Ronnie replied 1 year ago.
Hello and thank you for your question,Can you give me the actual fault code and or codes your getting?
Customer: replied 1 year ago.
I did respond to you question right away yesterday.I do not have the codes right now. The last 3 mechanics (including 1 ford dealership) said it was a general vacuum leak code but when they run the vacuum system test, it comes back clean. They replaced every vacuum hose they could find.The engine runs smooth as silk and starts every time. This is an "around town" car at this point. My wife drives it to get groceries. I spent a lot of money trying to get this problem fixed. I just want to turn off the indicator at this point. Is there a wire I can disconnect or is it difficult to get to the bulb?
Expert:  Ronnie replied 1 year ago.
Im just now getting your response but at either rate if you could get me the actual code it would be useful in trying to determine the cause. Most auto part store such as Auto Zone will run the scan for you at no charge.
Customer: replied 1 year ago.
Codes are P0171 and P0174
Expert:  Ronnie replied 1 year ago.
Okay, the fault codes P0171 and P0174 are lean codes and in most case are caused by an engine vacuum leak and the common leak in most cases providing you have proper flue pressure is usually a leaking PCV supply line. Start first with locating the PCV valve in the RH valve cover and follow it around to the intake where it connects to the upper intake and see if its rotted out. Its very common for this to happen and easy to over look because its hard to see it. Check this and let me know the results and we can work from there.
Customer: replied 1 year ago.
As I stated at the beginning, the vacuum lines have ALL been replaced on this vehicle by 3 different mechanics...including the line you have mentioned. The error is cleared and the engine is restarted, as soon as you get on the road and put the engine under load (like accelerating), the light will come back on with those codes. This has been going on over a year!My question was how to disable the check engine light!
Expert:  Ronnie replied 1 year ago.
There really is no way to disable the light beside removing the bulb. If you live in an area where emission testing is reguired doing so would be an issue.
Customer: replied 1 year ago.
I do not live in an area with emissions testing. This vehicle is in excellent shape considering the age and miles. As nobody has been able to fix the problem, I can't tell if something else is going wrong because I am ignoring it at this point. Soooo...what makes the difference if I remove the bulb? Is it difficult to remove the bulb?
Expert:  Ronnie replied 1 year ago.
Removing it will not hurt anything, to do so you will need to remove the instrument cluster to access it. Would you like the cluster removal steps?
Customer: replied 1 year ago.
sure
Expert:  Ronnie replied 1 year ago.
Okay see the steps in the link below, you will need to depower the air bag system before you remove the cluster. See the steps in the first link. Copy and paste the links to your browser to open and view them.https://dl.dropboxusercontent.com/u/104923897/depower%20Apr%2012.pdfSee the instrument cluster finish panel removal steps in this link.https://dl.dropboxusercontent.com/u/104923897/cluster%20finish%20panel%20Apr%2012.pdfSee the cluster in this link,https://dl.dropboxusercontent.com/u/104923897/Cluster%20Apr%2012.pdfSee the bulb replacement in this link.https://dl.dropboxusercontent.com/u/104923897/cluter%20bulb%20Apr%2012.pdfPlease take a moment to rate my service so I can get credit for my time, the question remains open for follow up even after doing so, all you need to do is return to this question if need be.Thank you again.
Customer: replied 1 year ago.
do you have an electrical schematic
Expert:  Ronnie replied 1 year ago.
Which circuit are you needing the diagram for?
Customer: replied 1 year ago.
the dashboard schematic
Expert:  Ronnie replied 1 year ago.
There are a total of 4 for the cluster. See them in the link below.https://dl.dropboxusercontent.com/u/104923897/cluster%201%20Apr%2012.pdfhttps://dl.dropboxusercontent.com/u/104923897/cluster%202%20Apr%2012.pdfhttps://dl.dropboxusercontent.com/u/104923897/cluster%203%20Apr%2012.pdfhttps://dl.dropboxusercontent.com/u/104923897/cluster%204%20Apr%2012.pdf
Customer: replied 1 year ago.
If I were to attempt to trace out all the possible causes of these 2 codes, how long would it take? You already described the PVC line...what other possibilities could there be..I was told there were a lot...
Expert:  Ronnie replied 1 year ago.
Both of these codes are lean codes and in 99% of all cases they are set due to a engine vacuum leak providing you have good fuel pressure.
Customer: replied 1 year ago.
have not had any problems with fuel pressure. The fuel pump was changed about 2-3 yrs ago...no problems with it.I'm sure the problem is the vacuum...I went out to check the pvc lines and found a bad transition boot feeding the air conditioning dampers...so I guess the other 3 "technicians" didn't see it so maybe they missed something else obvious. I replaced that transition boot and the dampers under the dash started working again...I didn't really know they weren't working since my wife drives this vehicle all the time and she never mentioned it. But I noticed on the way to the parts store the top vents wouldn't put out any air...once the boot was replaced, it works fine.
Customer: replied 1 year ago.
what else can I check
Customer: replied 1 year ago.
does the pvc line go up to a manifold of sorts?
Expert:  Ronnie replied 1 year ago.
You may have solved it by fixing the vacuum line for the AC, any type of leak will cause these codes to set. You can recheck the PCV line by locating the PCV valve in the right side valve cover and take your hand and follow the supply line around to the upper intake where it connects to make sure its not rotted out and leaking there, perhaps they may have missed this as well.
Customer: replied 1 year ago.
I had the codes cleared but they came right back. The PVC (at least I think it is the PVC) on the right valve cover has multiple hoses coming from it. I checked them out but didn't see and rotting or poor lines. If this isn't the pvc, let me know.
Expert:  Ronnie replied 1 year ago.
That is the PCV on the right valve cover. If the codes are coming back then something is still leaking.

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