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Discussion Starter #1 (Edited)
I wanted to start a thread to discuss how to replace the evap pump, as my car has been throwing CEL P2404 - EVAP Leak Detection Pump Sense Circuit: Implausible Signal. I've seen several threads on this, some of which are linked at the end of this post. It seems like most people have had to replace the evap pump and had a shop do it. There was also someone who had this CEL go away after replacing the gas tank cap. The part number for the pump is LF6618581A (at least for my 2008 i model USA non-CA), and is the white and black part shown in the following photo of the passenger side rear camber link area (stolen from Rotus8, link to thread).

So far, I checked the evap system for anything obviously wrong, like kinked hoses, as well as the evap air filter for clogging.

Questions that I still have after researching this issue:
Does anyone know of a thread with details on lowering the rear subframe? It seems like this is probably necessary in order to replace the leak detection pump. I've read of others who said it is simple to lower the subframe and that there are only six bolts, but haven't seen any instructions or pictures. I will take pictures if I do this myself. Or, is there an easier way to replace the pump?

Here is where the filter is located, inside the black plastic can at the end of the hose. It is behind a plastic shield that is seen after removing the rear wheel on the passenger side.

Here is the filter, which I tried to clean with compressed air.

Links to other threads about P2404:
http://www.mazda3forums.com/showthread.php?t=631025
http://www.mazda3forums.com/showthread.php?t=382546
http://www.mazdas247.com/forum/showthread.php?123774178-P2404-What-the-heck
http://www.mazda3forums.com/showthread.php?t=394037
 

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Discussion Starter #2
Page 01-16A-9 in the 2007 Mazda 3 service manual is on evap pump removal/installation. Rear crossmember removal is indeed part of the process (page 02-14-12), and while six bolts are mentioned, it is not clear where they are located exactly. Hope it will be obvious once under the car.

I've also learned that this is an intermittent monitor. I think that the evap check is run 4 hours after the engine is switched off. If the P2404 problem is detected once, then there is a pending CEL. If the problem happens on two consecutive evap tests, the CEL is illuminated. I'm monitoring the pending codes with my Ultragauge, and trying to look for patterns. Most likely though, the pump is just failing gradually and the I wouldn't be surprised if the codes become more and more frequent.
 

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I've replaced my EVAP pump, it had developed a large crack in the side and threw a gross leak code. I got an OE (only option available) for 130ish on amazon.
It was b**** to change out. I removed the RR wheel, had the car jacked up pretty high with numerous jackstands. I bent the metal bracket to access the torx fasteners.
I basically pulled the wiring loom loose from its home on the frame to give myself a little more length to work with.
It will be a pain, you will curse Mazda for basically building the car around this stupid pump.

But it IS possible without dropping the subframe.
 

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Discussion Starter #4
I've replaced my EVAP pump, it had developed a large crack in the side and threw a gross leak code. I got an OE (only option available) for 130ish on amazon.
It was b**** to change out. I removed the RR wheel, had the car jacked up pretty high with numerous jackstands. I bent the metal bracket to access the torx fasteners.
I basically pulled the wiring loom loose from its home on the frame to give myself a little more length to work with.
It will be a pain, you will curse Mazda for basically building the car around this stupid pump.

But it IS possible without dropping the subframe.
Great information, thanks for replying. I really don't understand why Mazda made this so difficult. I also ordered the OEM part and may attempt this weekend.
 

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I changed mine and it was a bit of a bitch to get out. Ended up dropping the tank. After dropping the tank it was much easier to access it.
 

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Discussion Starter #7 (Edited)
Somewhat strangely, the issue seems to have gone away on its own. I got the P2404 CEL on Feb 24, and the same pending code on Mar 2. Since then, nothing for 24 days of daily driving. I returned the pump, but if Murphy's law holds true and the issue comes back, I'll post pics of the replacement. Hopefully I can do it by bending the bracket or dropping the gas tank instead of dropping the subframe.

Edit, I'll also mention that my car is a 2008 i sedan with 68k miles.
 

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Can you just replace the filter or buy it separately? I don't have a compressor and I don't think I can clean it really well without one.

I am having a random P0446 pop up and I'm leaning towards it being dirty parts somewhere. I can clear it and it will come back eventually. I don't think the purge valve or leak detection pump are bad yet (although the purge valve seems cheap and easy to replace).
 

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Discussion Starter #10
Can you just replace the filter or buy it separately? I don't have a compressor and I don't think I can clean it really well without one.

I am having a random P0446 pop up and I'm leaning towards it being dirty parts somewhere. I can clear it and it will come back eventually. I don't think the purge valve or leak detection pump are bad yet (although the purge valve seems cheap and easy to replace).
I don't see the filter sold separately, just part number BN8B4256XC from various vendors of OEM parts, which is #7 in the diagram below. It's described as "hose" but I'm guessing that it comes with the filter as well.
 

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I don't see the filter sold separately, just part number BN8B4256XC from various vendors of OEM parts, which is #7 in the diagram below. It's described as "hose" but I'm guessing that it comes with the filter as well.
Thanks for the quick response; not what I was hoping for. Hopefully I can just clean it up.
 

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I'm pretty sure my filter is toast:









This was such a chore to open also (as you can tell from all the screwdriver marks). In between the gaps was filled with sand-I had to wedge 2 screwdrivers on opposite sides and use a third to pry it open carefully as to not break it.. The part itself is pretty easy to access, but I don't know where it (the hose) meets up to as the rear subframe kinda blocks your view.

I called the parts store and they couldn't help me out. I've been trying to find a filter using the number on the top with no luck so far.
 

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Hey everyone,

instead of spending $100+ on a "Mazda" part, just buy the Bosch one (it's the same; Mazda gets it from Bosch). For $50-$60 you can get a Bosch 0261222018 Leak Detection Pump which is the same thing.

Hope this helps,

-Mike
 

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Anybody replace LDP by dropping cross-member ?? I can see the 6 bolts but there are many items connected on both sides. I think you need only a few inches drop on right side to get enough access for LDP.

For vent filter, you can simply cut nylon pipe on vertical section behind wheel and join together with a new filter/pipe using 3 inch tubing and 2 hose clamps. (Its just canister vent for air).

Anyone know how the LDP really works ?? (no vacuum so must be all electric motor pump) ??

Thank you!
 
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