Hi i got two codes on my car

Hi i got two codes on my car Mechanic's Assistant: Just to clarify, what's the exact code? And have you tried to reset it? P0556 and p040f I reset the codes but they come back when I drive at 65mph for few minutes Mec...

Hi i got two codes on my car Mechanic's Assistant: Just to clarify, what's the exact code? And have you tried to reset it? P0556 and p040f I reset the codes but they come back when I drive at 65mph for few minutes Mechanic's Assistant: What is the make/model/year of your car? They illuminate the Red [brake](/topics-brake-ford/) light 2018 ford expedition Mechanic's Assistant: Are you fixing your Expedition yourself? What have you tried so far? I replaced the brake booster, checked the vacuum hose and pressure sensor on the brake booster. I also checked to make sure the wiring has power Mechanic's Assistant: Anything else you want the Mechanic to know before I connect you? No. Thats all

Automotive Expert
Hello my friend my name is \*\*\*\*\* \*\*\*\*\* welcome to JustAnswer. Hopefully I can help you with your troubles today. It looks like you have done the proper repairs for the code p0556. As for the code p040f that's for your egr. Approximately how many miles is on your vehicle and was the repair done at the ford dealer?

Hello DanWhat is the egr?[Mileage](/topics-mileage-ford/) is 15000 roughlythe car was repaired at ford when needed
Automotive Expert
Ok that;s great because it should be covered under warranty. EGR is your [exhaust](/topics-exhaust-ford/) gas reciculation. P040F means that there is discrepancy between the primary and secondary egr temp sensors.

Unfortunately the car is not under coverage and this is why I am using your service hereI am sure this two codes are caused by one issue since they come to the scanner togetherAny idea how these two codes are related and what is the source of this problem?
Automotive Expert
Oh wow ok. Sometimes after these new vehicle needs the pcm reprogrammed after a part replacement. The only thing I can think of is maybe there's a vacuum leak somewhere around the [engine](/topics-engine-ford/) , because both the brake booster and the egr works with vacuum.

The vacuum system in this car is huge. How can I do smoke test to find the leak,if there is any?Any idea what is the pcm oem part number for this car so I can find it out
Automotive Expert
The easiest way is have the vehicle running and spray it down with a spray bottle of soap and water while the engine is running. Unless you have a smoke machine and you can put it throw the intake manifold .

I have no idea how to do the smoke test on this huge car. Any advise?Are you sure the egr is also works with vacuum?Any idea if this is a electrical issue (cut wires or programing) or mechanical issue (vacuum leak)? How can I distinguish these two?
Automotive Expert
It doesn't work with vacuum but is attached to the manifold.First do the spray test if the idle doesn't fluctuate then is not a vacuum leak. Was the vehicle in an accident or flood.

The car was in an accident.I fixed all the issues and the last issue is when I drive the car in highway 65mph and more for 4-5 minutes, the car gave me a message "check brake system" and also the red brake light turn on. If I drive it below 55mph for a long time no light turns on.It was the main issue.Now, some thing crazy happens and the car turns on, but dont go to ignition and does not drive. If I wait a day, it might go to ignition.Basically it run whenever it wants.Any idea if this is related to the vacuum issue or separate issue?I have a f-150 which has many similar parts like the expedition so I could test some of the vacuum parts by swapping those between the cars.test themAt this point, I was totally confused what is the issue and how to proceedI had this issue once and a electrician checked my car and said the connection behind the brake booster and brake pedal was loose and this was why the car was not start. He fixed it but now the car has similar issue which I doubt it is the same old issue. Any idea on these problem?When the car does not start, it gave me many U... codes for miscommunication.Plus some parking sensor message, [coolant](/topics-coolant-ford/) message and some other non sense messages. Does it help to discover the main issue?

Are you here?
Automotive Expert
I'm hear i was just reading everything.

Oh ok
Automotive Expert
Where was the hit from the accident.

Front driver side
Automotive Expert
Was it major or minor.

AverageNot minor, not very bad. I say average accident
Automotive Expert
You would need a scanner that can read scopes and signals. You need to determine if those sensors are communicating with the computer or vise versa. When accidents happen ,you don't know if wires got crushed , or even if a module is not communicating with the pcm.

The car was runnable for a long time. I drove the car to an electrician and he used his scanner. He said the issue could be one of the sensors on the vacuum hose or potentially a leak in the system. I swapped the hose and it was fine now the only thing it can be (as you mentioned earlier) is to check the leak (smoke test).You mentioned I can spray soap and water and see if rpm change while the car is idling, right?
Automotive Expert
but use a spray bottle.

Any idea if the leak is the cause of the car not cranking the car?

The second code I receive now is P040f , buy I was getting P050f few days ago which is for brake assist vacuum too low. Does this help you to better understand the issue?
Automotive Expert
No that will not cause a no-start condition. For the P040f and P050f yes a vacuum leak can cause that

Any idea how I can use the smoke machine for this huge vacuum system in this car?
Automotive Expert
I would say connect it to a hose that goes into the intake manifold.

Now it gives me P0453 code
Automotive Expert
Ok that codes is telling you that you have a evaporator leak which is a vacuum leak so would definitely have to smoke it.

The problem was the brake booster. I replaced it and every thing works fine now.
Automotive Expert
Oh nice to hear that I'm so glad for you, was the first brake booster defective?

The gasket between the brake booster and master cylinder needed to be adjusted.
Automotive Expert
Oh ok glad to hear you got thru .

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