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08 Cayenne S codes P2181 and P2404

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Hello all, I got these codes on my Cayenne and am geting conflicting stories from the dealership. Concerning the P2181 code they are telling me I need to change the cooling pipes on my 08, which I thought already had the aluminum pipes. What I would like to know is, what do (and should) I change other than the thermostat? Any advice would be very helpful. Concerning the other P2404 - please give me some direction. I'd like to do this work myself and am aware of a special tool that I may need top purchase or borrow. :wrench: :thumbup:



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P2181 Thermostat Blocked - Implausible

Possible fault cause- Thermostat blocked open- Faulty engine temperature sensor

Note:- The fault is stored if the engine is not heated from below 40 °C to over 60 °C after throughput of a defined air mass. This indicates that the thermostat is blocked open.- An unchanged temperature signal may also come from a faulty sensor. Check fault memory entry.

P2404 Evaporative Emission System Leak Detection Pump Sense Circuit Range/Performance

Possible cause of fault- Insufficient vacuum (system has a leak or blockage)- Short circuit to B+ in signal line- Leakage diagnosis pump faulty (diaphragm or reed switch sticks, internal solenoid valve stays closed or is blocked)- DME control module faulty

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Wow, you are good. would you happen to know any recommendations to be done while I am switching out the thermostat? Also changing the housing, hoses, etc.

On that secong one I am confused, where should I begin?

Are there any TSB's?


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Does your Cayenne still have the plastic cooling pipes? If so, then start there and inspect the thermostat to be sure there are not broken pieces in it.

Several good write-up here if you search and look in the DIY Tutorials section.

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I have an '08 "S" as well, and have gotten 2181 regularly (about 3x per year) Since it is very unlikely to be the thermostat with this infrequent occurrence, I have been happily ignoring it. I'd clear the codes and see how quickly it reoccurs.

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Was just in another forum and they is a big issue with these plastic cooling pipes and which years have them. My understanding is that the (03-06) 955 4.5 engines are having these issues and I'm hopeful that Porsche corrected the issue for the next gen 957 4.8 engines. My view is this, since I'm going to be in there anyway I might as well replace the pipes if they are still plastic. I plan on keeping this Pepper for a while so I really prefer for it to be worry free especially since I live in 100 plus degree temps. Anyone here have any experience on this?

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957 has got plastic pipes although different design to the 955.

No upgrade aluminium pipes for the 957 as have not been known to fail like the 955.

No need to be concerned.

Blocked thermostat every 300 - 400 miles seems odd.

I'd be checking the temp sensor connections first.

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Good information. I have code P2181 displaying the CEL. No abnormalities on the temp. Not saying that it blocks every 300-400 miles just that the CEL comes back on after being cleared. After codes are cleared the dash displays SERVICE NOW every start is this for oil change? I just bought this Pepper and was going to do any maintenance now. Also, got code P2404 this last time but I'm not sure what the reed switch is.

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as far as the other codes: P12A1, P2181, and P2404 are all active. The Pepper is idling rough now and takes along time to start. I dont want to drive it until I figure this out. Please help

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So as of today, I went out and rescanned my codes and this is what I get now: P1026, P050D plus the other 3 that I posted: P2181, P12A1, and P2404. Needless to say that todays start was the worst and it had a horrible idle. Anyone?

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So, I replaced the High Pressure Fuel Pump and that was the root of all the other strange codes. It was not as tough as I imagined and I hope to have the write up soon. Pretty simple just detailed job.

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There is a TSB 0701 for your car. It was issued on 10-29-07. The repair is to replace the thermostat housing and thermostat.
Thermostat Housing is 948 106 060 05
Thermostat is 948 106 125 01
There is a note to always check the repair history to see if the housing has already been replaced because any fault code p2181 stored after 10/07 may have already had the thermostat housing replaced.
I had to replace and if my memory is correct,the new housing has a green mark, whereas the defective one has yellow.
I also replaced the water pump because it began to leak as a result of the crappy thermostat.
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  • 1 month later...

Hello jcvara,

Any updates on your p2181 code? I have a 08 cayenne S 81,000 miles and am now getting the p2181 about every 300-400 miles or 17 warmup cycles. I believe it is definitely the thermostat in our cars. The freeze frame data shows the temp to be 145 deg F at the time the code sets which I believe rules out the temp sensor. There is not aTSB for these engines and thermostat as mentioned in this thread but for the sleeve with 2 o-rings that runs between the thermostat in its housing and the water pump. This was replaced under warranty at the dealer at 40,000 miles and can be accessed from the front by removing the water pump or from the top by removing the intake and thermostat housing. These are the same ways to access the t-stat.

PS Also noticed that the coolant level was low by about 60 ounces, which was pretty low for the coolant level low light NOT to come on. Since I topped off about 2,000 miles ago it has remained full but p2181 still repeats.

Any input would be very appreciated?

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  • 5 months later...

I have the same 2181 code and took my 2009 Cayenne S to the dealer for repair under aftermarket warranty. Found out warranty doesn't cover the repair. Dealer quoted $1300. Can you provide a description of how to get at the waterpump to change the thermostat? I do all my own work on my 911 and have changed water pumps on other vehicles but not on this one.

Any advice on the repair and any other parts necessary to do the repair (i.e. gaskets etc) would be appreciated.

Thanks in advance.

Dave T

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  • 2 weeks later...

FYI I did the thermostat replacement last weekend and posted a DIY today. It is a straight forward project which takes between 4 and 5 hours. Cost for parts is around $70 from Sunset Porsche.

Hope the DIY helps anyone who is going to do the thermostat replacement.

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