[foxmajik]

Today on the way home from work the MIL (check engine light) came on in my car.

When I got it home the first thing I did was call the dealership to ask them if they could look at it. Of course they told me they were closed today.

So I thought I'd have a shot at diagnosing it myself.

I got out my trusty ELM327 OBD II to USB adapter and plugged it into the diagnostic port, then started up scantool.net's scan tool software.

When I read the scan codes from the ECU I got a code of P0455 (Generic Evaporative Emission System Leak Detected [gross leak/no flow]), which I looked up on Google, where I located this article.

I knew I didn't have any of the testing tools but I read through the article anyways, which informed me that one of the first things I should check is "a loose, incorrect, missing or damaged fuel fill cap."

I checked the gas cap and found that it was loose, so I screwed it back in.

I knew from pervious research that the ECU would turn on that DTC code if the engine was started twice while the problem still existed, so I started and stopped the engine three times to verify the check engine light wouldn't come back on.

EDIT: This problem was fixed in the 2009 model, it has a loose filler cap indicator on the console.

 

[tomFS08]

Thanks for the info.

-Tom

 

[foxmajik]

Hey guess what, in the 2009 fortwo they put in a light on the dash to tell you if the gas cap is loose.

I can't imagine any more sound acknowledgment of a problem than putting an extra lamp on a new model to help the owner fix the problem so I don't understand why there has been no offer to fix the problem for owners of existing 2008 year model cars.

 

[Dave777]

.

I don't understand why there has been no offer to fix the problem for owners of existing 2008 year model cars.

I sincerely don't intend to sound sarcastic, but I have to ask what you expect the dealer to do to "fix the problem?"

It's a loose gas cap. Happens to good people who own every kind of car out there. They get the same check engine light and from then on they make sure they screw the cap on until it clicks. Problem solved.

 

[Jordon]

Hey guess what, in the 2009 fortwo they put in a light on the dash to tell you if the gas cap is loose.

I can't imagine any more sound acknowledgment of a problem than putting an extra lamp on a new model to help the owner fix the problem so I don't understand why there has been no offer to fix the problem for owners of existing 2008 year model cars.

What do you expect, smart to call and have you bring the car in so they can change the cluster to include a new light, reprogram the car to turn that light on instead of the CEL, just so you can fix a problem you caused yourself and not take it back to them. FYI, most manufacturers will only cover checking the light once for this, if you go in a second time they will charge you.

 

[gnarles]

Gas Cap caused CEL to stay lit

My wife used my car the other day and put gas in it. She brought the car back to me and the CEL was on so first thing I did was check the gas cap. It was loose so I tightened it but the light did not go out. I ran a diagnostic on the car and got a po455 error (loose gas cap) even after putting the cap on correctly and going through several start ups, I've even added gas myself and still the CEL is lit. Any ideas on how to simply turn off the light ( reset it) to see if it comes back on meaning I may have another problem besides the loose cap? The MB dealer here tried to charge me over $100 for an oil change and wanted me to leave the car when I can have it done for $8 plus oil and filter at my neighborhood mechanic while I wait.... needless to say I don't want to have to deal with the dealership.

 

[jwight]

Zombie thread! Like a lot of other error codes, this one may take several start cycles to go away. Keep driving it as normal and the light should go out. If not, it's probably something other than the gas cap.

PS - does your car have the loose gas cap warning light? If so, did it come on?

PPS - did you check the rubber gasket itself? The only time I had this happen it was the gasket not properly seating, in spite of my usual 3+ clicks.

 

[Brabus007]

3 Clicks is the proper number of clicks...

 

[jwight]

Or 4 or 5 or 6....:wink:

 

[Smart Bob]

CEL ON:

You need to erase the code. Most code readers, Scanguage, Ultragauge, etc. will let you erase the code. If you have a Pep Boys near you, they will usually do this for free. If the code returns, then you have another issue like some debris under the cap, etc.

 

[Rustedwrench]

My wife used my car the other day and put gas in it. She brought the car back to me and the CEL was on so first thing I did was check the gas cap. It was loose so I tightened it but the light did not go out. I ran a diagnostic on the car and got a po455 error (loose gas cap) even after putting the cap on correctly and going through several start ups, I've even added gas myself and still the CEL is lit. Any ideas on how to simply turn off the light ( reset it) to see if it comes back on meaning I may have another problem besides the loose cap? The MB dealer here tried to charge me over $100 for an oil change and wanted me to leave the car when I can have it done for $8 plus oil and filter at my neighborhood mechanic while I wait.... needless to say I don't want to have to deal with the dealership.

The fault code sets when the test for the sealing ability of the evapoative emissions system fails a leak test. The test only runs under very specific enabling conditions and may not run every drive cycle. Generally, on most vehicles the test only runs under specific temperature ranges and the fuel level between 15% and 85%. The test must pass several times before the control unit will extinguish the check engine light. You can either keep driving or clear it with a scan tool.

 

[gnarles]

Thanks jwight, I'll check the gasket. I don't have a seperate gauge I have an '08 451.

 

[gnarles]

Thanks rustedwrench, I guess I'll just keep driving it for awhile. The scanner I own will retrieve codes but will not let me clear them.

 

[smark]

Might have a leaky Evap canister. That will give you that message too. Been there.

 

[SmartDigger]

I drove my 09 with the cap light 80 miles with the cap off and no light on. it is a random check

 

[gnarles]

Smark is there a way to test the canister myself or does that have to be done at a shop? I have the Chiltons manual but didn't find any info other than how to remove and replace.

 

[RickyM]

I think most cars will throw a code if the gas cap is loose. Both my honda and toyota do. I filled gas one time while leaving it running and had the code already when I got back in the car.

 

[smark]

Smark is there a way to test the canister myself or does that have to be done at a shop? I have the Chiltons manual but didn't find any info other than how to remove and replace.

Have to do a smoke test. To buy the equipment is very $$$$. Don't know if you can rent them. Had to have dealership do mine.

They replace several gas caps. Wasn't the issue. Small leak in the system. Check this site out.

http://www.motor.com/article.asp?article_ID=543