rbf41000

My CEL came on last Friday, no drivability issues.
Used my generic OBD2 scanner and showed no codes and pass, looked at the reset and it won't reset the CEL as it shows okay
Took car to the dealer and they say it needs a new gas cap and charcoal canister for $1700, i'm going to get a second opinion.
When I asked about why it needed a gas cap AND canister, they told me a bad gas cap compromises the canister, bear in mind this car is a 2018 with about 17K miles and I never top the gas off and the CEL came on with around a half tank of gas so I had done at least 150 mikes since fill up probably a week ago, any thoughts?????

57 GTR

MB TAX,lol

Acta_Non_Verba

Single biggest contributor to killing the canister is topping off, which you said you don't do. Topping off essentially drowns the canister in fuel. It was only meant to handle fumes and not liquids. Difficult to understand the correlation they made to the cap...but they're getting paid the big bucks, so.....

Many miss this message on the fuel lid.... in caps:


EDIT:

Hi RBF,

I only had a few minutes to answer this last night.

Codes related to the evaporative system are all generic P-0xxx codes (such as P0455,0456,0457, etc.) that a generic scan tool should read. What about your scan tool? Is it a canbus tool? Is this the first time you've used it on this car? Older scan tools can't link up to canbus and you'll know if the tool just reads "link error"

On the gas cap, the only failure here would be the seal. There are other components to the evap system too such as the purge valve. Solenoid, etc. The canister is expensive though and some work too.

rbf41000

Thanks for the answer, my scan tool did finally link, I had to use the key in the arm rest rather than the push button. P044200 and P045600, both small leak in evap system
I did not let the dealer do the work but cleaned my gas cap and put it on and off a few times then cleared the codes, so far the car has run flawless for many miles and many stop starts with no codes or CEL.
Time will tell though as it is nearing needing the tank filling, I think I will put a new gas cap on though for peace of mind.

Acta_Non_Verba

Hi RBF,

You might have solved it just with the gas cap. You have codes for a small leak detected in the evaporative system (circuit). One of the possible causes IS a gas cap that doesn't seal. If cleaning it up then clearing the faults, and the CEL doesn't come back, then you've found the small leak. Otherwise, if the cap didn't solve it, the CEL would be right back on.

Well, that might have saved you a "few" dollars!....good for you! Hope it stays that way for you.

All the Best,