roach2012

I believe the all the Cayennes & Panameras have the same evap system, along with the bigger Audi's & VW's (i found this info on a VW site). When i replaced the LDP, it & the vacuum line were flooded with oil (i now know this was due to the failed vacuum pump as you pointed out). But the oil did stop the LDP from even performing the test, subsequently triggering P0455. To clear the line there are some good tutorials on how to get to the carbon canister assy, but this is what i did: - unhook vacuum line in engine compartment - jack up rear right side - remove rear passenger wheel - remove wheel cowling - look up & un-hook carbon canister 3 x bolts - un hook the vacuum line, the smaller pipe going in to the top (solenoid part) of the LDP - blow air in from the engine side (used a small electric air bed inflator) - wait & see what comes out. I'm still not sure if you can salvage an LDP once its flooded with oil could be worth a try if you can pull it apart. When its working normally you should be able to hear a clicking sound as it opens & closes.

Yeah that lower bolt was a pain, especially with what i think is the steel PDCC line over it. Ended up giving it to a mechanic to fix, which to their credit they did well. there may be oil in your vacuum line to the LDP left over from the failing vacuum pump, un-hook it at both ends & blow some air through fixed that on mine (after also replacing the LDP) All codes gone now but still getting large puff of smoke on start up (every 2-3 days) & an occasional large puff during acceleration.

Kino, you could be right. After replacing the LDP the code went away for a week or so & has now come back twice. Are there any good DIY's for replacing the vacuum pump ? i see one on Pelican parts but i appear to have an extra metal line for the hydraulic sway bar completely blocking access to the lower bolt.

Thanks for taking interest, In this case after testing the LDP the P2404 code was set by the leak detection pump when it was full of oil possibly form engine blow-by of some kind (bad check valve or bad engine TBD) Either way the oil must have been on/around the reed switch causing an electrical fault & a bad signal (oil is conductive &/or just sticky) , it seems to have cleared up after draining. Still have P0455 though. Currently waiting on LDP delivery from an online supplier. 1/2 to 1/5 of dealership price depending on which you call VW/Audi/Porsche, all our EVAP systems seem to be exactly the same. I have also ordered a couple extra check valves to place on the vacuum line just upstream of the LDP to stop the back flow of oil. If this fails over time there is space in the wheel well for a small catch can. The vacuum pump seal could very well be the source of the oil, but it is currently generating the 19 InH20 pressure at the LDP which is plenty & a healthy whooshing sound if i open the oil cap. I think the real solution if that is the case is to address the blow-by in the engine. so to date : P0455 Evaporative Emission System Leak Detected (large leak) Possible causes: 1- Tank cap not tightened correctly, faulty or missing- ---- Nope 2- Mechanical fault in EVAP canister purge valve (does not close fully) ------ Nope 3- Leakage diagnosis pump leaking internally (membrane) or externally ---- Posable, EVAP side not leaking but oil in the electrical plug means there must be some communication between the vacuum line & the atmosphere, shouldn't directly cause a P0455 though. 4- Mechanical fault in EVAP canister shutoff valve (does not close fully when power is supplied) ---- Posable 5- EVAP canister shutoff valve connections leaking --- fixed 6 - Tank system (including pipes) leaking --- nope just a note i think 3,4,5 are all the what is sold as the LDP Would anyone know there the vacuumed air goes to after the vacuum pump? & would anyone know how to trigger the Evap self test, i'd like to see if the canister shut off works with a smoker.

After looking at a few more diagrams there there a couple of options but i don't really understand any on them fully. 1 - its back flowing through the vacuum line (which was also full of oil) , kinda posable given that this is a turbo but I'm not sure on how exactly the pressure would get reversed. The positive pressure at the LDP solenoid could explain the electrical plug filling with oil though. There is a good vacuum in the crank case when the engine is running & the oil filler cap is removed, not likely a vacuum pump issue. 2- coming through the carbon canister but how would oil get in a carbon canister ? maybe the purge line ? Are there any other possibilities ? would anyone know what to look for regarding likely failed components ?

Thank you for the huge post, very informative ! Another sad story from a long time forum lurker, with a 2008 Cayenne TT I have the same (ish) problem, symptoms include: -P2404 & P0455 - Puff of smoke on start up (every 2-3 days) -In addition I'm seeing an occasional (once every 2 weeks) idle drop & engine vibration when coming to stop. I have a smoker & the Durametric cable to perform the diagnostics but can not find where you activate the purge valve with the scanner (if anyone knows that would be great!?) Checked the gas cap for seals tightness, cleaned it up, looks immaculate, 100% isn't the cap after the smoke test Pulled the purge valve connection& can not blow through the purge valve at all when the engine is off. Opened up the rear wheel well & inspected the Evap canister, which looked good but there is engine oil all around it, Pic attached. looks like its seeping out from the connection between carbon canister & the LDP. Performed smoke test any way & zero leeks not a puff until i opened the gas cap to confirm the tank was full of smoke, it was. Pulled the carbon canister to access the LDP connection & i found that the electrical connector was filled with oil. Connected a 12v jumper & can hear the solenoid click but in any state or polarity it passes smoke. i have ordered a new LDP diagnostic pump but would like to know: How the heck did engine oil get to the back of the car ? thank you in advance.

Same situation here Cylinder # 5 Trady have you found any innovative solutions that work or at least seem promising ? To the best of my quite limited understanding, the whole block is Alu-Sil, so re-honing would be a simple job (to those who can).

Same problem, any DIY advice would be appreciated

Bump?

Update: My issue was the back pressure retaining valve located directly on the shock where the air hose connects, it had seized up & essentially became a one way valve trapping the max pressure in the cylinder at all ride height settings (made one corner 1" higher than any other & the car cornered like crap). Easy to diagnose if you have the same symptoms. 1) place jack under suspected corner 2) remove pannel covering the compressor & valve body 3) unscrew the suspected line to that corner, they are labelled on the valve body & if the air hissed only for a second (or 20) & the corner doesnt lower on to the jack then its likely that your valve is bad replacing it is slightly more complicated

Update: My issue was the back pressure retaining valve located directly on the shock where the air hose connects, it had seized up & essentially became a one way valve trapping the max pressure in the cylinder at all ride height settings (made one corner 1" higher than any other & the car cornered like crap). Easy to diagnose if you have the same symptoms. 1) place jack under suspected corner 2) remove pannel covering the compressor & valve body 3) unscrew the suspected line to that corner, they are labelled on the valve body & if the air hissed only for a second (or 20) & the corner doesnt lower on to the jack then its likely that your valve is bad replacing it is slightly more complicated

i have noticed the came thing, did you find the cause ?

did you ever manage to solve this problem , my rear is high & front is very low

mine still will not rise during the calibration test. but i do get an error 2250 my front values are 190 mm and rear are 237 mm, you are saying i should enter the front as 200 mm ?

Yep the second i hit the switch during the test causes the test to fail, but will raise the car. if try to go in to Low manually i am seeing an error code 2250 seems to be a valve but i don't know which one. One thing i have started doing is just guessing the values (i know dumb) before the car returns to normal level, don't do this. The front is way lower than i have ever seen it before @ now won't go up. It probably had something to do with hitting save when the front was in the low setting; saving 190 mm with low.