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

Thank you for responding. I have an appointment with a Chevrolet dealership to have the system completely checked. I will let you know what they say.

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

To give you an update. the dealership said it's the canister, that it has dust in it and said the oil pressure switch and harness needs to be replaced.

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.

Latest update. The dealership told me that the charcoal canister and purge valve solenoid needed to be replaced. So, after spending over a $1,000.00 and only driving 113 miles the check engine light came back on with the same code. I'm very upset after spending this amount of money. after all being a dealership, they should know what they are doing. so, I have two questions. isn't the charcoal canister a completely sealed part? And second what would be your next step in finding out what the problem could be?

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.

It keeps mentioning the control module. Which one is it talking about?

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.

Thank you for clearing up which control module. so the BCM (body control module) has no function in this?

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

Just to give you an update. The dealership this time said it was the purge valve, after making sure that the new parts were working that the tech noticed that there was pressure building so, they replaced the purge valve. So, I will let you know if that fixes the problem.

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.

Another update: The dealership replaced the purge valve and this time at 72 miles the light came back on. I am so frustrated with all this. they have replaced the charcoal canister, the purge valve solenoid, and the purge valve. What else is there to replace or look for? I asked if there was a fuse that could be causing the light to keep coming back on and they said no. so far, I have spent over $1,400.00. Any more ideas?

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.

Now the dealership is saying that it's the fuel tank. It's holding pressure but not vacuum and the fuel pump needs to be replaced also.

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.

Good advice and that is what is in my plan. I agree about the fuel pump. I will let you know what happens next.

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

This is what the dealership said, they go from one component to the next to try and fix the problem. So, they said the canister and purge solenoid wasn't working. And when that didn't take care of the problem, they replaced the purge valve. And that didn't work they narrowed it down to the tank and fuel pump. To me if you bring it in because of the light it seems to reason to test everything and then fix the first time. I think it's all a money thing. All together it has cost me $2,400.00 and I don't know if the problem is fixed until I get it back and drive it. Question: is it possible for a fuel tank to hold pressure but not vacuum?

That is just not true, and this is what gives dealerships a poor reputation. This is such a shame that they are trying to tell people this.

How could all these parts fail at the same time for them to all cause the same concern?

This system just doesn't work this way and clearly, they are just telling you this, so they don't have to give your money back. You are correct that they can test each one of these parts and they either pass or fail.

I am sorry, but I guarantee you if you put all the original parts back on after they find the actual faulty component that they will not cause the light to come back on.

Trust your instincts, because you are correct. If you are not dealing with the service manager at this point, I would be. If you are then go higher in the dealership, either the GM or the dealer owner.

Basically, all you need to stand on is you brought the vehicle in with a code and $2400 later you still have the same code.

I don't know what state you are in, but most all have small claims court that was designed for this. Again, I am not trying to wind you up, but this just is not right.

If this turns out to be a fuel tank pressure sensor then you paid thousands for a $50.00 part.

The fact that they are recommending a tank and fuel pump (that most likely comes with the pressure sensor) just is further proof they have no clue. See the picture below.

This code is telling you that over a certain period of time with the engine off, the fuel tank pressure is not correct. Normally it is too low which means there is a leak or the PCM thinks there is a leak. The system could be fine and just have a faulty sensor giving the incorrect reading.

Based on all this, if they are going to guess, why have they not guessed with the cheapest of all the parts in this system which is the fuel tank pressure sensor?

To answer your question, in theory if something can hold pressure then it can hold a vacuum. However, this system is not meant to be pulled into a vacuum. I have actually seen fuel tanks get collapsed in on themselves when the vents are clogged, and the pump pulls fuel out and it doesn't all air in to equalize the pressure when the engine is running.

Please let us know what happens. Thanks

I will definitely let you know. And thank you.

You are welcome. I have hopes that they will do the right thing, you may just need to get to the right person in the dealership.

Thanks

This is the latest update. Finally got my car back after 2 weeks. I'm attaching the notes from the dealership. He also said that with my system that it checks its self in the mornings.

I am sorry that this is happening to you. It very well could be a fuel tank, but I don't see in those notes the proof that they found the issue.

The only thing that they gave that was solid info was the data from the code showed that the decay rate was higher than expected which indicates a leak.

However, if they can't find a leak then it may not actually be leaking. The fuel tank pressure sensor may be reading incorrectly which makes it think it is leaking. So, if they are checking the pressure on the tank and it is not dropping off then they need to monitor the pressure sensor with a scan tool and find out if this is dropping when the actual pressure is not dropping.

As for it checking it in the morning, this is not true either.

The PCM monitors the pressure at given times after you shut the key off. So, at each check point of the key off time, it expects to see the pressure at a certain point or range. If it is outside that range, then it sets a code. This is telling you at the point it is checking it, the pressure is too low, so it assumes there is a leak.

This happens every time you shut the truck off, it does not check it one time in the morning after you have let it sit.

Again, sorry but they clearly are not familiar with this system.

By now you're probably tired of hearing from me. anyway, got my car back and the light came back on this time at 18 miles. I took it back and of course they are baffled but said for me to bring it back in this Monday. I told them what you have said about the fuel pressure sensor. the service advisor acted like he has never heard of it; this is the last chance. If they don't fix it this time, I guess I would have to take legal action. any thoughts or advise on where to start?

It's not that I don't want to hear from you but sorry that we are hearing from you on this type of issue. Hopefully, we get some good news soon.

They need to monitor the pressure in the fuel tank and then monitor the fuel pressure tank sensor using a scan tool. These two should be reading the same thing.

If they replaced the pump, then they need to confirm it came with a fuel tank pressure sensor as it is mounted on the top.

However, I don't think they are going to fix this thing, at least I don't have high confidence that they will.

What I would suggest is if you are going to give them one more chance then that is fine but if they don't fix it, then you should ask for your money back and you basically go somewhere else and start over.

If they don't return your money, then you can take legal action. As long as they continue to work on it then you technically don't have a case. They either need to refuse to work on it or refuse to return your money.

Basically, you paid them to fix it and they either need to do that or return your money.

Good morning, hope you had a good Christmas and hope you have a safe and happy new year. I know it's been a few weeks since we last talked...the dealership has been waiting on another part to come in. A part that joins the fuel filler tube to the tank. Anyway, I took my car to my regular mechanic to get the oil changed, since it was there, I had him do another smoke test and once again he said there was no leak, period. He suggested that it could be a programming issue. How would I find out if it is. I've read that Chevrolet did have this issue with the Chevrolet Cobalt with the same code. my mechanic even mentioned this.

I got an email saying that my last email was answered but I don't see the response.

I don't know if this has any meaning, but the last two times the code was reset it came back on at exactly 18 miles.

Also, my phone lets me know when my messages are read, but I have not received anything back.

If there is an issue with the fuel tank pressure sensor, then that will not show up with a smoke test because it is not leaking externally.

If there is a "programming" issue, then that would be found using a scan tool as I suggested above.

As for getting these messages, they are marked read with any expert read them so I suspect someone else viewed it, but I am sorry for the delay.

Thank you. I'm going to ask them again about the fuel pressure sensor.
Do you think that the light comes on at exactly 18 miles?

Yes. It sounds like a failing emission code. They are normally pretty close to the same drive time and distance when they fail if they are going to fail.

Especially if you are taking the same route when it fails at the 18 mile mark.

I am sending attachments of the tech's notes. Each one is in order of the work done. This is number 1.

This is number 2.

This is number 3.

This number 4.

This is the diagram they gave me and telling this is what is needed. The long hose part they have but the fuel filler tube has been discontinued and if I get a replacement that isn't gm factory, they can't install it. They first said they would install the part they do have but later on they called me and said they weren't. And that there nothing else they can do.

They told me to call the smog referee and explain what the dealership said. I have called the smog ref and was told that my car had to fail smog. spend $650.00 to try and fix it...and if it failed smog a second time that they could give me a waiver on the smog. And that all the money I have already spent does not count.