Check engine light turns on with code P0144

Did you remove the oil fill cap to find out if the smoke was leaking out of the crank case? Also, we need to remove the air intake tube to see if it is coming out of the intake. Basically, I suspect you have a leaking purge valve.

I understand that the shop told you all the valves are operating but this is commonly missed.

However, if this was not and the system truly has no leaks then the likely cause is the fuel tank pressure sensor is faulty.

Basically, we need to monitor the voltage and find out what it is doing in order to know for sure.

https://www.2carpros.com/articles/how-to-check-wiring

I am attaching all the info below on this system and sensor.

Please run through this and let me know what questions you have. Thanks

Sounds great. Yes please let us know because I am curious about this one. Thanks for the update.

Okay. Thanks for the update. The oil pressure switch and harness sound like a different issue.

However, the canister sounds like it has fuel in it, or the vent is leaking. If there is fuel in it then we need to check the purge as well as that could be sticking, or it is going to stick. Fuel breaks down the charcoal and causes it to get the purge to stick.

Thanks for the update and using 2CarPros.

To start if you paid for this specific issue to be fixed, I would take it right back to them and tell them they did not repair it. If they try to tell you this is a different problem but the same code due to it going over 100 miles, then that is not true. This evap code, after cleared requires to fail the test a number of times before it turns the light back on. This test requires certain drive cycles and engine off time for it to meet the parameters to run the test. This can take over a hundred miles to happen, so they clearly did not fix it.

The canister is completely sealed from allowing vapor to the atmosphere but when the purge valve opens, it allows this vapor into the engine so that it can burn it and reduce emissions.

Please review the documents I attached prior for more info on this.

These evap issues are hard to find but I am attaching below the tests for each part of this system.

The only way to find this is to run through all these tests.

This is talking about the engine control module (ECM). It is possible that this is the issue, but it is the least likely cause.

Just from experience and knowing that these are difficult issues to fix, I suspect they missed something and did not find the fault.

Correct. On this vehicle the BCM controls the functions that are more related to the "body" of the vehicle like the lighting, anti-theft, HVAC, wipers, door locks.

The EVAP system is directly related to the emissions of the engine and is controlled by the powertrain control module.

Let us know if you have other questions and how this turns out. Thanks

Well, that would make sense. It will be interesting to see if this is the issue.

Thanks for the update and let us know how it turns out. Thanks for using 2CarPros.

It sounds like they are guessing at it and just clearing the code. As I said before this will take about 100 miles to run through the system test to determine if it fails.

If it were me, I would be calling the manager and tell them what is happening.

These are difficult issues to find but they need to find what the fuel tank pressure sensor is doing.

Basically, the way this small leak test works is on every time the engine runs and then shuts off, it checks for a large leak. If the large leak passes, then it continues to check the fuel tank pressure over time while the engine is off.

If there are no leaks, then the ECM expects to see a certain pressure in the fuel tank after a certain amount of time. If this pressure is lower than it expects to see, then the ECM assumes there is a leak in the system.

This means, the purge or vent solenoid could be leaking. The fuel pressure sensor is not accurate. Or the ECM could the issue.

Unfortunately, they only way to know this is to test the system as I am attaching below.

What I suspect is happening is the mechanic that is working on it, doesn't fully understand the system and how it works. Clearly this is based off only what is in this post but from my experience with mechanics, this is a complicated system to understand but once you do, it is pretty simple.

If they already replaced the canister, purge solenoid and the solenoid again, then they have to test the other components as shown below.

If they are charging you then ask for a copy of the technician notes so we can see the reasoning behind this.

This is basically the testing that the tech is performing in order to prove this out. If it makes sense, then great but I don't know what the fuel pump has to do with this. If they are not charging you then go for it. If it doesn't fix it then you got a tank and fuel pump out of this.

However, no matter what I would start asking for all the parts that they are replacing because if it doesn't fix the vehicle then there was nothing wrong with it and you can keep them as spares.

However, this is called a "comeback" and they should either be refunding the money you have paid to correct this concern and then charging you for this or they should be paying for this on their own.

Basically, you presented the vehicle to resolve this issue and each time they told you it was, and you paid the bill only to find out that it is not.

Repair shops try to claim that the parts replaced previously were defective and needed to be replaced however, that is rarely the case.

I am not trying to get you worked up but in my opinion, this dealer does not know what the issue is and keep taking the best guess. If it were me, I would be demanding at this point that they fix this at their expense, and you will continue to bring it back for this code until it is fixed. They keep making a repair, clearing the codes which requires the vehicle to be driven for close to one hundred miles before the light would be turned back on.

Sounds great. We will wait to hear back. Thanks for the update.