Happy New Year - Sad Old CEL Problem
 

Happy New Year

After 6 months effort, I and my independent garage are still trying to chase down my CEL problem ((P0410 and P1410 only). We've done all the usual stuff and replaced all the mechanical and electrical stuff in the secondary air system as well as the MAF and O2 sensors. We've even replaced the gas cap as some have suggested.

Here my question. If a leaking gas cap can cause this problem, I wondering what other gas system problems might also be the the cause. For the past eight or nine months, I found it hard to fill the gas tank without the pump nozzle clicking off multiple times thinking the tank was full. Could there be something going on in the gas fill system that would be tricking the computer in to throwing the codes?

I'm grasping at straws here, but so far nothing has kept the light off beyond the short period the system needs to reinitialize.

Thanks

Do you have this problem at all gas stations? I avoid one of my local gas stations because of that same issue.

As for the gas cap, that is a source of vacuum leak if the seal is bad.

The P0410 code is one where having access to a Durametric software system becomes indispensible as it can test components rather than blindly replacing them; the diagnostic tree starts by triggering the secondary air pump using the “drive links” capability of the software to see if it runs, if it does not, you need a new secondary pump. From there, look at all the various vacuum lines for leakage points (visual inspection); then the system triggers the electric change over valve, and finally the air change over valve. If all these check out, try blowing out the air supply lines for blockages. If nothing at that point, start looking at the DME.

As for your second code, are you sure it is not a P1411 rather than a P1410? The reason I ask is that a P1411 is related to the P0410 (same code for the opposite cylinder bank)

As for problems filling up, it is not related to the other codes, but is model year dependent. First, look at your filler neck (cap off) and you will see a flap; push it open with your finger and you should head a loud “click” of a “flapper” valve opening lower in the fill neck. If you do not, check your E6 fuse to see if it has blown, that will cause this issue. If yours is one of the early cars (99 and earlier) and the E6 fuse is OK but you do not here the “click”, there is a lower “flapper” valve in the fueling system that gets blocked by vent lines and tends to cause problems, and is somewhat more difficult to fix. The one way flapper type valve is at the junction of the filler neck and the tank, and is there to allow gas in but not out. There are vent line tubes in the tank behind the valve that can slip down preventing the flapper valve from opening allowing only the filler neck to fill up then slowly seeps by the valve, causing the slow fill/no fill phenomenon. The repair is not hard, but you need to pull the fuel tank (do it while the tank is empty) to get at the lines.

If memory serves, there are TSB’s for both these fuel tank issues.

This may have nothing to do with your problem, BUT , the previous owner told me to change o-rings next year on the dip-stick, oil cap,rad cap and to replace the gas cap (again) because of strange CEL's. I have his receipt from Porsche last year for the amount of $66.54 for all. No more CEL's for him. I checked the oil yesterday and noticed the dip stick had a little "play" in the sealing (o-ring) I just might replace again soon. $00.91 # 999-707-366-40 AIR LEAK !!!