0455 Fault code question

[KarlT]

Hi all,

My name is Karl and I am the new owner of 2001 996 with 29K miles.

I have had the car about 2 weeks and I have had the 0455 fault come on twice.

When I removed the gas cap to check for bad o-ring I noticed a hissing noise ( which lasts about 10-15 seconds ) which would tell me the fuel system is holding pressure

Any ideas

Also, Thanks in advance for all the info I have obtained from this site prior to buying my vehicle, I felt like I was going into this car purchase a lot more informed!

Karl

[Loren]

:welcome:

P0455 Fuel Tank Ventilation System (Major Leak) -- Below Limit or Signal Implausible

Possible causes:

- Tank cap missing

- Cap seal

- Ventilation lines detached from EVAP canister

- Ventilation line detached from tank

- Ventilation lines detached from operating purge valve

- Ventilation line detached from EVAP canister purge valve

- Break in ventilation lines

No signal

- Pressure sensor

[KarlT]

Loren

Thanks for the quick response, so it is normal to hear the hissing noise when gas cap is removed?

The fault implies pressure is too low? But the hissing would imply pressure?

Just trying to wrap my head around this

Thanks,

Karl

[Loren]

Yes, the hissing implies pressure.

The problem could be a bad valve or line to the release side of the valve.

Further inspection of the lines and valves is needed.