I have a 2004 CTT.

P2403 came up after I repaired all vacuum leaks.

I changed Purge Valve, Leak Detection pump, and checked emission hose leak

but CEL won't go away.

The strange thing is

After I fill up gas full and clear code, CEL won't show up until half empty of gas tank.

If the gas tank has gas below half, CEL on very soon after I clear the code.

Any idea?

Please, help me.

 

Is this the "large evaporative leak" code? If so I replaced my gas cap when I started getting the code. I noticed if I tightened the crap out of the cap when I got the code it fixed it for awhile. So buying a $20something cap and installing it was the easiest thing to try first.

Worked like a charm, no codes since.

 

Check the gas cap first for proper seal. Then check fuel and vent lines for any damage or leaks.

 

No large evap. leak code.

p2403 is only code.

Even so, still you think I should change gas cap?

One more thing, how about CEL acting weird when tank is full and below empty?

I check many hose from canister to purge valve but I can't find any leak.

 

http://www.ecstuning.com/Porsche-200...ions/Fuel_Cap/

"One more thing, how about CEL acting weird when tank is full and below empty?"

^This makes no sense.

You could take it to the dealer for an obcene amount of money, or you could try a drink of the cheap water you were led to. Are you sure you really want help?

 

I bought new fuel cap yesterday right after 2 people suggested it.

While waiting shipping, I just think if the CEL caused by fuel cap, the CEL on

regularly no matter how much fuel is in the fuel tank.

As I posted,

"After I fill up gas full and clear code, CEL won't show up until half empty of gas tank.

If the gas tank has gas below half, CEL on very soon after I clear the code. "

Strange.

 

Well that actually makes some sense. When the tank is full the system registers fine but as the level goes down if the cap is leaking the system senses the leak and triggers the CEL.

I'm no expert, I just know what worked for me.

 

so, u also had p2403?

while waiting new cap, i used plastic wrap and rubber band to seal the filler neck.

i will see if the cel won't come again.

 

I don't remember what the code was I had. But if you've replaced everything else the cap is sure worth a fairly cheap shot.

 

I changed
fuel cap and I am still getting CEL

With generic OBD reader: p2403

with durametric: p2451


So far,

I changed fuel cap

I changed purge valve twice

I changed leak detection pump.

I changed canister + another leak detection pump.

I don't think there is actual leak.

No problem with filling gas.



Is there somewhere else I need to look??

 

Hi chunki , looks like you have tried about everything, I have seen in very rare cases a leak from the tank flange cause this issue. It is very hard to diagnose and usually requires smoke test equipment to verify. It will sometimes cause a light raw fuel smell right after a fill up. The tank flanges (2) are accessed from under rear seats by an access cover under carpet. Left flange is also the pressure regulator , the right flange is also the fuel filter .They are plastic flanges with o-ring seals that can get a hairline crack over time and cause a leak to the evap/fuel tank system .I suggest you take it to a professional to test and repair this due to the fact that you will be dealing with an open fuel tank and dangerous fuel and vapors that will have to be removed while this repair is done .

 

I am thinking maybe wires go bad which connects with canister and leak detection pump and filler neck pipe(brown ground wire)

Because some of electric circuit died.
GPS signal died(inside of rear spoiler)
Rear hatch won't open by switch and remote (changed latch and actuator and still not working)

If wires are bad, is there some way I can locate the problem spot?

 

Yes a simple DVOM (digital volt/ohm meter) can test ground , power supply and all fuses.