Code P0442, fuel leak around fuel filler neck while pumping gas?

KIWASABI1

MEMBER
2001 MITSUBISHI ECLIPSE
2.4L
4 CYL
2WD
AUTOMATIC
246,000 MILES

Hello 2CarPros,

I hope you are having a good day. I've long had a persistent P0442 trouble code and haven't been able to identify the leak. Now I'm thinking I may have found the source of the leak. Please see the video I've attached. This happened while I was pumping gas this morning. After I had driven to work this morning, I checked it again and did not see any leak happening. So, this appears to only happen with the added pressure on the system from the gas pump while pumping fuel. Does this mean I need to replace the fuel filler neck? Thanks for all the help you guys have provided me already.

Thanks,

Adam

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5 Replies

AL514

MECHANIC
4,677 POSTS

Hello, is that leaking out of the bottom of the gas tank? The video is a little difficult to see. And what sub model is this vehicle RS, GS or Spyder GS? Are you pulling the gas handle out to try to fill the tank to the max limit? This P0442 is an Evap system small leak detected. The Evap system is for fuel vapor management, I'm wondering if that gas leak is coming out the top of the gas tank.
This is a diagram of the Evap vapor system and gas tank, the Evap system purges fuel vapors into the Intake manifold so they can be burned and not released into the atmosphere. But driving around with a gas leak like that is extremely dangerous and is actually illegal. If they saw a leak like that at the gas station, they would make you have the vehicle towed to a shop and the fire department would be called, I have run into that before with a customer at a shop I was working at which was part of a gas station. So, you need to get that fixed before driving any further.

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Thursday, August 10th, 2023 AT 11:41 AM

KIWASABI1

MEMBER
198 POSTS

See attached image. It was definitely the fuel filter neck; it was completely rusted out on the bottom. I ended up buying the OEM part MR573836 off eBay for about $190 after tax (see 2nd pic). The OEM part is metal whereas aftermarket fuel filler necks are plastic. I've also been having some issues with aftermarket parts not always being an exact fit. Anyway, we got the new part on there and the leak is gone, and so far, the P0442 code hasn't come back. It seems the P0442 code is common on these cars, so anyone reading this with that code on a 2000-2005 Eclipse should check the fuel filler neck. Since it's metal it rusts out over the years.

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Wednesday, August 23rd, 2023 AT 12:42 PM

AL514

MECHANIC
4,677 POSTS

Glad you got it fixed. The P0442 is a common Evap Small leak code, I surprised that all it set for codes, which looks like a large evap leak to me. If you live in an area where they use salt on the roads in the wintertime, the wiring harness under the vehicle will eventually rot out, so if you get further codes in the future for any Evap or oxygen sensor type codes, that will be the first area to check.

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Thursday, August 24th, 2023 AT 1:10 PM

KIWASABI1

MEMBER
198 POSTS

I live in Colorado, so we do have loads of salt on the roads during wintertime. I did have issues with the wiring on the driver's side of the engine block with all the transmission speed switches. That was more likely melted by heat through. The only other code I had was P0421 Warmup Catalyst Below Efficiency. I cleared the codes about 3 or 4 days ago and so far, P0442 and P0421 have not returned. There's no way the leaky fuel filler neck could have caused P0421 is there? I bought some Dura Lube Extreme Catalytic Converter Cleaner that I'm going to try. I'm going to use it right before going on a long 60-mile drive and see if that helps the catalytic converter.

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Thursday, August 24th, 2023 AT 1:17 PM

AL514

MECHANIC
4,677 POSTS

For the Cat warm up, it depends on if the ECM (engine computer) was still purging vapor from the Evap system due to that small leak code. I would think it wouldn't stop purging completely because the fuel vapors have to go somewhere. They can't just be released into the atmosphere. When the computer is purging fuel vapors it opens the purge valve which pulls intake manifold vacuum on the gas tank and being that the vent valve is open at that time as well, it does cause a lean condition. But not that you have it repaired correctly, I wouldn't worry about it too much unless other codes start to set. Most codes take a certain amount of drive cycles, especially the Evap system. There needs to be a certain amount of fuel in the tank, certain temperatures, etc. So just see what happens in the next few days. I used to live in Colorado, a beautiful place.