# small EVAP leak



## aries68 (Dec 11, 2011)

My 'Service Engine Soon' light came on my 2004 Nissan Frontier S/C Crew cab and when a scanner was 
plugged into the truck, the unit read 'small evap leak'.
Has anyone had this problem.


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## csagenlee (Oct 18, 2010)

More than likely you have a vacuum hose leaking. It has either rotted away or the connection is loose. My truck throws the same code every now and again and it is usually a vacuum hose.


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## smj999smj (Jan 1, 2006)

The evap small leak code can be pretty vague. Basically there is a leak that could be as small as the head of a pin somewhere in the evap system. Most common problem is usually an incorrectly installed gas cap, but can include such issues as the previously mentioned leaking vacuum hose, a stuck open vent control valve, leaking evap canister, leaking fuel tank sender "O" seal, a bad evap pressure sensor...to name a few. Sometimes the fix is as simple as reinstalling the gas cap or making a visual inspection of the system...and sometimes the only way to isolate the source is using a "smoke machine" hooked up to the evap test port and a scantool.


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## aries68 (Dec 11, 2011)

A 'smoke machine' was hooked up and no visible leaks were found.
Also I changed my gas cap with a factory cap and still the same code comes up.


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## smj999smj (Jan 1, 2006)

Might want to check the evap pressure sensor, then.


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## aries68 (Dec 11, 2011)

Is that sensor located above the spare tire?


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## smj999smj (Jan 1, 2006)

Somewhere in the back... It looks like same as a boost sensor and is the "eyes" of the EVAP system.


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