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So I swapped the dirty paper air filter last night for a K&N drop in replacement. I took it for a ride, for about maybe 5 miles or so. When I went to work this morning, the "service engine soon" light came on. Since I was out and about to go pick up spark plugs/wires, I stopped by a parts store and they connected their scanner. It reads:

Code: P0455 GENERIC - Evaporative Emission System Leak Detected (gross leak/no flow)

Well, here, here's a couple pics of the scanner, I don't know if there's any other relevant info here:



Could it be that a piece of debris/dirt/oil/what-have-you got onto my MAF, and that's what's causing the service engine light to come on? What should I check for? What should I do?

I should also mention, that I did use the rubber gasket piece that came with the K&N, and it made snapping the clips to the airbox back into place rather difficult....but I figured that was good because it would provide an extra tight seal. I felt all around the main intake hose (the large hose from the airbox to the air intake on the engine) and it felt seated all the way around. I do not believe there are any openings or leaks that would compromise dirt or debris getting in that way.

That's a evaporative emissions code, similar to the "check gas cap". The fuel tank pressure sensor isn't seeing the proper vacuum being established during the test. Your air filter shouldn't affect that. Check to be sure the gas cap is on tight, and seals properly. Also, see if you may have knocked a line loose from the evap solenoid, or from the throttle body leading to it. There are many possible causes for this, including: defective evap solenoid, or vent valve; bad gas cap; rust around the filler tube; broken or clogged evap lines; leaky canister; or defective fuel tank pressure sensor.

Archon wrote:That's a evaporative emissions code, similar to the "check gas cap". The fuel tank pressure sensor isn't seeing the proper vacuum being established during the test. Your air filter shouldn't affect that. Check to be sure the gas cap is on tight, and seals properly. Also, see if you may have knocked a line loose from the evap solenoid, or from the throttle body leading to it. There are many possible causes for this, including: defective evap solenoid, or vent valve; bad gas cap; rust around the filler tube; broken or clogged evap lines; leaky canister; or defective fuel tank pressure sensor.

Okay, I have been away from my car since I posted. I will check the gas cap. I believe I can rule out rust around the filler tube - or - if there is, that would be pretty much the ONLY spot on the WHOLE car where there's rust. I just looked underneath it on a rack a few days ago - looks real good. Spotless. I'll get under the hood tomorrow and check the lines to the evap solenoid. I don't recall knocking anything around near it (although I just learned where it was...). So, regardless of where it's coming from, am I right to assume that A.) this will decrease my fuel economy, and B.) if I don't like "service engine soon" lights then I should get it taken care of?

A. It's possible, depending on the cause.
B. Yes,.

I just put a new gas cap on, from the dealer. As I understand it, once the leak is no longer there, it takes cold starting the engine three times before the code will clear itself. $25 after tax for an OEM gas cap. Nickels and dimes, oh my. Here's to hoping and praying it was that.

Question: If my fuel economy is up to snuff and I'm getting what I should be getting, is this really something I need to worry about? Indiana doesn't do emissions testing, and it seems like that's mostly an emissions thing. Just wondering if it will affect engine performance or not.

Without knowing for sure what the cause is, it's hard to give a real good answer to that. Is it likely to cause any serious damage? No. However, if it is a vacuum leak, the engine won't perform as well as designed. Also, there are certain timings for tests that the system does. If it receives a fail for a test, it does not go on and perform the rest. That can also cause less than optimum performance.

I had a 2000 Ei on which I was chasing the gas cap code around. Turned out to be the first the vent valve. Then, the gas cap. Even though the engine seemed to be running fine, I was surprised on the difference when I reset the code.

Another issue with ignoring it is that if another code is set, you won't know it since the light will already be on. That's assuming the new code isn't for some obvious engine malfunction.

Mark Fahey wrote:Another issue with ignoring it is that if another code is set, you won't know it since the light will already be on. That's assuming the new code isn't for some obvious engine malfunction.

Very very true, and I thought about that. That's why I think I'm going to invest in a Scan Gauge II, I meant to do it for my '97 but never got around to it, but a Scan Gauge II is on my short list, for that reason and obvious others.

If that tool you have resets or erases codes, then go ahead and erase the code and see if it returns...

Just to note my 3.05 Loaded heavy SLE does 21 City and 29 Hwy... I get patches where I do 30-31 as I am not doing time travel...lol

So you should do in 18-30 area depending on fuel blend and cold start temps...

so ludichris did the three cold engine starts and new gas cap solve the problem...because i have been battling this issue for a while now

DASHAWN1234 wrote:so ludichris did the three cold engine starts and new gas cap solve the problem...because i have been battling this issue for a while now

Nope, sure didn't. Service engine light is definitely still ON. Ordered a Scan Gauge II today, should be here in a few days. At least I can then clear the code to see if it returns.

In other news...my fuel economy was 17.5 MPG - mixed highway/city. NOT good!!!!! Something's definitely wrong there.

i changed both of the vent solenoids and had my sel reset by auto zone and the light came back on in one day...just trying to see what else i can try

Ludichris wrote:

DASHAWN1234 wrote:so ludichris did the three cold engine starts and new gas cap solve the problem...because i have been battling this issue for a while now

Nope, sure didn't. Service engine light is definitely still ON. Ordered a Scan Gauge II today, should be here in a few days. At least I can then clear the code to see if it returns.

In other news...my fuel economy was 17.5 MPG - mixed highway/city. NOT good!!!!! Something's definitely wrong there.

When you get the scangauge see if you can monitor the O2 Values and Cross counts.... Wondering what condition the O2 is in...

ludacris, any updates? I am having the same problem. Tried the gas cap first. No luck.

cosmicdust wrote:ludacris, any updates? I am having the same problem. Tried the gas cap first. No luck.

No, but I bought a Scan Gauge II, so it shows up about every 400 miles or so, and I just clear it. I haven't noticed any affect on fuel economy, so it's just annoying. Scan Gauge - scan - read codes - clear codes - done.