P 0455 code
 

I'm getting a P 0455 code, emission system leak, major leak fuel tank vent system, confirmed on my 98 Boxster.

What can it be besides a fuel filler cap?

Thanks!

Could be the cap, or a major leak in the EVAP system.

P0455 is for the EVAP canister purge valve -- could be a short circuit to battery + voltage or a short circuit to ground in the wiring from the control relay to the purge valve -- the control line to the valve from the relay is pin 2 on the valve (pin 5 on the relay). Of course, the last entry in most diagnostic procedures (for any OBD2 car) is that the engine control module has a problem.

Regards,
paul...

JFP replied b/4 I did, and since he's a pro with yrs of experience. I'd listen to him.

P0455
 

02 Boxster 160,000 miles, original clutch and Idler shaft bearing!! Replaced cap, CEL stayed on, replaced cap-activated valve at top of filler tube on outside, left reed switch out, no light but couldn't fill fuel, put reed switch back in place verified audible click when filler port gate is opened with finger, but CEL is back p0455, is canister purge valve the culprit? conflicting locations one is on the engine below intake manifold, one is on top of canister, which is it? SmileWavy