alfcruiser

Hello Folks,

Every time my check engine light comes on, I tighten the fuel cap and the light usually goes away within a day or so.

Will changing the fuel cap fix this? Has anyone replaced their stock fuel cap and gotten this to work?

BTW, this is for a '98 ML320.

Thanks,
alf

pcy

It might just be that you are not tightening the cap
enough. I've learned that if we tighten until we hear
atleast 2 clicks, then I don't get the check engine light.
If I just tighten it barely (meaning no clicking sound),
then I am certain now that I will get the check engine light.

So, for the next few refuelings, try tightening the cap
until you hear several clicks. See if that fixes your problem.

If the problem persists, the gasket in the gas cap is probably
worn out.

Good Luck

alfcruiser

Yeah, mine does the same thing. But I guess it must be a worn gasket.

Not sure how much they go for, but gonna replace it to fix this annoying problem.

Thanks,
alf

Swiss Nick

Hi guys. I'm reading your post in disbelief. Are you saying that the sensors on the ML are even rigged to the fuel cap?? or is it because it is a pressurised system? I'm not taking the ****, but it seems incredible that the engine warning light would be affected by the fuel cap. Please let me know any info you have on this, thanks.

Nick

GDawgC220

yes, the fuel tank is pressurized. If the cap is not on tight enough, as in leaking vapors out, it will trigger the check engine light. Once you tighten it, it will go out in a little bit. All MB tanks have been presurized for a long time now as well as many other car manufacturers.

miguel446

I know they've checked caps during inspections here in the states for years now. What's the reason for a pressurized fuel tank?

M