P0456 persistent after replacing fuel cap

[Dotpage]

Hey fellas, I replaced my fuel cap about a week ago after a P0455 and P0456 on SES and "Replace fuel cap" lights came on.

light stayed off for a couple of days after I reset, and now every other day I get P0456(small leak).

Any ideas?

[danewilson77]

Mmm... Thinking.

HTC Thunderbolt+TT

[kayger12]

I remember reading something about a vent valve for the fuel tank or something like that... that goes bad and needs to be replaced.

I'll do some digging.

Droid X. Tapatalk. Use it.

[Dotpage]

Found and will try this:


Just a follow-up update after I replaced the EVAP purge valve (a.k.a. fuel tank breather valve) on my 2002 BMW 325i (E46). As I did it, I discovered that all that needs to be removed is the air filter housing in order to get access to replace the EVAP purge valve. It turns out that I didn't have to loosen the power steering reservoir retainer and move it out of the way. There is enough slack in both fuel breather hoses that you can slightly unhook the purge valve from the mount and slightly pull it out from under the engine intake manifold.

Before I started the replacement work, I first disconnected the negative terminal at the car battery to kill power to the car. Then I began work by removing the 2 bolts holding the air filter housing with a 10mm socket. I also had to unclip the 2 metal clips holding the round air intake boot to air filter housing. After I unclipped the clips, pull the round intake boot from the housing. Separate the other plastic retangular-shaped intake on the opposite side of the top portion of the air filter housing from the housing by squeezing the plastic retangular-shaped intake as you carefully pull the rectangular intake and the housing apart. There is another plastic rectangular air intake connected to the bottom portion of the air filter housing with a grey foam seal around the inlet; I left this air intake connected to the air filter housing. Now, I carefully lift out the whole air filter housing. After I removed the air filter housing, I just followed NoVaDreier's instructions (previous posted message) for the EVAP purge valve replacement. I've cut-n-pasted and italicized his instructions below:

After removing the air filter housing, the fuel tank venting valve is located right under the front corner of the intake manifold directly behind the power steering fluid reservoir. See the bottom picture on page 113-7 of the Bentley manual. According to TIS 13 90 500, (1) disconnect the electric plug connection on the front of the valve, (2) release the bottom vent hose by pressing the locking bar and detaching, and (3) detach the rear hose from the venting valve.

A couple of footnotes...in order to separate the electric/power plug connection from the purge valve, there is a small metal wire clip I had to depress. The plug connection slides off the purge valve easily when the metal wire clip is pressed. Also it helps to apply a little Vasaline petroleum jelly to the plastic hose barb of the new purge valve; the breather hose slides back on the new purge valve easily if you apply a little Vasaline. After I completed the replacement work and reconnected the car battery, I also used a handheld OBD-II code scanner to erase/reset the old purge valve error code from the vehicle computer. The "Service Engine Soon" indication disappeared and the OBD-II scanner showed zero error codes which hasn't re-appeared. That's great news!

Tools I used:

- Ratchet with 10mm socket (used to loosen/re-tighten nut on negative terminal of car battery and to remove/re-install 2 bolts holding air filter housing to the top of the front driver's wheel well)

- Flat head screwdriver (used mainly to assist in unlatching the 2 metal clips holding air filter housing to the round intake boot)

- Pliers (used to pull the larger breather hose off from old EVAP purge valve...I'm talking only about the hose without the plastic compression clip on the end. The other breather hose with the plastic compression clip can be disconnected using your bare hands)

- Vasaline petroleum jelly (applied a little to the plastic hose barb of the new purge valve...it made sliding back on the larger breather hose to the new purge valve much easier)

- Actron PocketScan OBD-II Code Scanner (used to erase/reset the initial purge valve error code from the vehicle computer after I replaced the valve...the "Service Engine Soon" light turned off after reset it and it never came back on)

- Evaporative Emissions (EVAP) purge valve [BMW lists the part as a Fuel Tank Breather Valve...part# 13901433603] - approx. $80 from the dealer

[danewilson77]

OK....sounds good Ed.

[kayger12]

Yep-- that's the thing I was thinking of.

[Mtnman]

I did that replacement. Super easy (5 mins) and part can be found at autohausaz (throught he site of course!) But yup, thats what my problem was (after I bought brand new bmw cap)
I didnt disconnect the battery, nor did i reset with a code reader. It will clear itself.

[Dotpage]

part # on autohausaz?

[danewilson77]

http://www.autohausaz.com/html/brandnames.html

[Mtnman]

13901433603

Fuel tank vent valve/breather valve. It is under the fuel/air systems category.

Although I swear the code i got was P0444 when i replaced this. See my thread about it here.