E36, help with P0455 Code <--------------------------

[Msilvia]

I recently pulled a p0455 code for EVAP emissions control system leak detected (no purge flow or large leak).

I've taken the rear quarter panel apart, checked every line going to and from the expansion tank. The tank itself doesn't have any visible cracks or old hoses. I have also checked the charcoal canister including the lines that route to it, nothing. I didn't suspect the gas cap but changed it anyway, cleared the code, and it's back. I'm officially stuck.

Anyone else had this issue? What other components should I be checking? Is it possible for the fuel pressure sensor to be faulty, causing it to throw a code?I have a feeling it is a very small issue that I am overlooking.

Help is appreciated

[bmwless]

Free bump, i`m in the exact same boat as you. I`ve been getting the code intermittently, mostly when i`m cruising at a consistent speed on the highway which I guess is when the system purge`s. Changed the gas cap and cleared the code but then it came back. I`m going to take the evap purge valve out and give it a look, maybe they clogged ?

[Msilvia]

Free bump, i`m in the exact same boat as you. I`ve been getting the code intermittently, mostly when i`m cruising at a consistent speed on the highway which I guess is when the system purge`s. Changed the gas cap and cleared the code but then it came back. I`m going to take the evap purge valve out and give it a look, maybe they clogged ?

Mine is on consistently on once the evap system goes through it's cycle. Have you checked your expansion tank and lines(behind passenger side fender lining)? That is the biggest culprit for this code on these cars.

[jasonn]

Maybe the gas cap seal?

[Marv17]

I'm in the same position too. I've checked my carbon canister and it looks good. And also the expansion tank doesn't hv cracks in it. I've replaced the gas cap and purge valve under the hood. I'm stuck what else to check. Is it the fuel pressure?

[Msilvia]

Maybe the gas cap seal?

Checked that, looks good.

I'm in the same position too. I've checked my carbon canister and it looks good. And also the expansion tank doesn't hv cracks in it. I've replaced the gas cap and purge valve under the hood. I'm stuck what else to check. Is it the fuel pressure?

I'm thinking it could possibly be the fuel pressure sensor.




Anyone else have any info?

[Marv17]

You Mena

Do you mean the fuel pressure regulator? I don't it would be that. I swapped mine out and still hv a code. Unless both regulators are bad then I'm not sure...

[Msilvia]

You Mena

Do you mean the fuel pressure regulator? I don't it would be that. I swapped mine out and still hv a code. Unless both regulators are bad then I'm not sure...

No I mean the fuel tank pressure sensor on the vapor expansion tank, in the right rear quarterpanel.

[sak335]

I had a similar problem last year. It took me weeks to find the problem. That vapor expansion tank has an internal check valve. You can't see it, but it's in there. I pulled the tank and shook it and heard nothing. Put air hose in all the openings and blew compressed air into them and heard the valve "knock" when it was forced open. Then, shaking the tank produced a rattle. Code gone, problem solved; valve was stuck closed now it's free to move like it is supposed to. Not saying this is your problem, but it fixed mine when all the other stuff checked out OK.

[bmwless]

Mine is on consistently on once the evap system goes through it's cycle. Have you checked your expansion tank and lines(behind passenger side fender lining)? That is the biggest culprit for this code on these cars.

Yeah I had a good look in there when I was doing my rsm's. Both the lines and tank looked good

Maybe I'll pull my expansion tank too and give it a once over

[Marv17]

Dang. Really? I've looked at it but never rattled it since I didn't think there was something in there. I can't remember any wires to it. I'll look into it. Hopefully my expansion tank is the same or similar in my 318ti. My problem happened after I swapped out my manifold to the m50 manifold on my s52 in the 318ti.

[Regamaster]

Marv17 and bmwless, did you guys ever find your solutions? (Sorry for the old thread bump)

I got the code on my 98' M3 a few months after I got it, cleared the code, then did my M50 manifold swap, code came back anyway.

Now I just replaced the gas cap with a new one from pelican and while I was at it, I pulled the expansion tank. No leaks or cracks found, valve inside freely rattles when I shake it, and also shot compressed air into the tank and held all the ends revealing no pressure loss. Now I gotta go buy 6 new metal screw clamps tomorrow and seal it back up.

The only other idea I have is replacing the purge valve under the hood but that parts costs almost $100.. Somebody please halp me.

[sak335]

The purge valve is easy to test. Pull it (easy - one bolt and a couple vacuum lines) and using test leads (or plain old wire with the ends stripped) hook it directly to the battery. You will hear a distinct "click" when the valve opens with power, and hear it click again when you remove power. If your valve is indeed bad (rare), I have a tested spare I'll sell you for $20.

If the valve tests good, then you need to get a Mityvac (or similar) and test all your vacuum lines to make sure they don't have splits or cracks.

[1019]

Do you smell gas when the tank is between 3/4-full?
If so there may be some hairline cracks on your fuel level sending unit

[MarketMaster]

I had the same problem and sure enough, it was the gas cap.

[drummel1]

Mine was caused by one of the nipples from the tank breaking off in the line for no apparent reason. Hence, a major leak. For those who haven't yet, I'd start there. Apparently its a common failure.

[merlinfe]

I had the same problem and sure enough, it was the gas cap.

Gas cap eh? Sounds like an easy place to start. I've been having the same problem. I too checked the evap in the right rear quarter and everything seemed in good order. Its got me scratching my head and I hate hate hate staring at the damned check engine light when I drive.

[Regamaster]

Replacing the Purge Valve solved my problem. No CEL (P0455) in months, just a heads up.

[Hitmachine101]

there s vacume hose and nipple under the s52 manifold that decided to pop off on me, kept getting that code for the longest time, once that vacume line ( which ran from a solonoid thats bolted to the bottom of the car right behind the drivers front wheel welll ) went back on and stayed on that nipple under the rear of the mani closer to the firewall, code has never returned

if you ve ever had your mani off the car ( that hose being disturbed ) id look into that being a culprit

[Marv17]

Replacing the Purge Valve solved my problem. No CEL (P0455) in months, just a heads up.

Which purge valve did you replace? The one under the hood or the carbon canister one?

there s vacume hose and nipple under the s52 manifold that decided to pop off on me, kept getting that code for the longest time, once that vacume line ( which ran from a solonoid thats bolted to the bottom of the car right behind the drivers front wheel welll ) went back on and stayed on that nipple under the rear of the mani closer to the firewall, code has never returned

if you ve ever had your mani off the car ( that hose being disturbed ) id look into that being a culprit

I hv replaced that one and I still hv the code. I got the code after I did the m50 manifold mod. Been wondering if I should swap back :frown:

[Regamaster]

Fuel tank breather valve under the hood, picked it up from a local JY for $5 bucks. Passed emissions and the car pulls stronger since I don't have to reset the computer anymore.

Hope this helps.

[Calical E36]

BUMP BUMP BUMP <-- can someone please tell me why people write bump? anyway.. I had a code P0455.. I took the expansion tank out, no cracks no broken hoses. I shook it to hear the rattle, which it did so the valve wasn't stuck, blew compressed air and all the holes flowed nicely. expansion tank checked out. A buddy told me the charcoal canister in the trunk, if its bad, feels heavy and worn, and if you disconnect it, has a raunchy old decayed gas smell to it. it felt light, no cracks or bad hoses so I left it alone. I replaced the purge valve today, and needless to say, my EVAP module finally cleared. hopefully it stays that way and I get smogged soon.

[merlinfe]

Mine ended up being the evap tank by the gas cap. I had to take it out and reseal one of the vacum hose attachments.

It looked fine from underneath the car but once it was out it was FUBAR'd. Some JB Weld and copper tubing fixed my issue and it never returned.

Your results will vary, I'm sure.

[Mandrew98]

To properly diagnose an evap code first thing to do is find someone with a smoke machine and pressurize the system with smoke. After that if there's no leaks, actuate the purge valve with a power probe at 12v dc. If that's working follow down the vacuum diagram actuating leak pump, canister purge, ect. Sometimes you'll need to clamp the hose at the canister unless you actuate the canister purge valve to hold in smoke. The valve at the canisters fail, purge valves at intake fail, leak pumps fail(if equipped) and vacuum lines leak too. Avoid throwing parts at it. Proper diagnosis will save money and get it fixed on the first try. If this is out of your league, find a good smog tech(good ones can be hard to find) and pay him 100 bux to diagnose it for you. It'll save you money on part throwing.

[andmatth]

Hey sorry for the old thread bump. I have the P0455 code and the check engine light is driving me crazy. I was wondering if you guys could help me pinpoint this issue. I haven't noticed any power or engine problems with this but when I put gas in my car I have to hold the pump handle at a specific angle or it shuts off (like the tank was full). Anyone else have a similar problem or know of what usually causes this?