Porsche Cayenne brake booster failure warning   3 comments

We are in the process of diagnosing this 2005 Porsche Cayenne Turbo S that has a warning on the insturment cluster indicating "Brake booster failure". We have checked vacuum to the brake booster and the electric vacuum supply pump. We are suspecting the booster itself. It has a pressure / vacuum sensor and a travel sensor in it. There are no codes in the ABS system or engine system — just the warning on the dash. Access and testing is quite time consuming. Will post the fix when we find it.
This warning would come on for 10 seconds when the vehicle was started and then just the small brake warning would remain lit.
The brake booster held vacuum, pressure and travel sensors tested ok. Brake booster replacement did fix this problem but double check the vacuum line as ours was brittle and broke as we were removing the booster. Vacuum brake booster line cracking is a common problem — especially at the line just under the electric vacuum assist pump.

Posted December 27, 2008 by jayauto in Porsche

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3 responses to “Porsche Cayenne brake booster failure warning

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  1. Help very much appreciated…. I have recently experience the same problem in my cayenne turbo 2003. I had change the brake booster, sensor and had checked all hoses and pump with no leak. Having canceled the error code on many occasions, the brake booster fault code will appear after 10-15 mins. I don\’t know what else to do, the mechanics reckons it might be a problem with the ECU… Appreciate if you can provide me with some advise.


  2. I have a 2005 Cayenne Turbo and the problem is the plastic lines used in the vacuum system. These lines crack causing the system to lose pressure resulting in loss of vacuum and potentially resulting in loss of vehicle control due to the inability to reliably brake at speed. I lost vacuum at low speed and had difficulty bringing the 5,600 lb vehicle under control. This is an issue affecting a safety system on a high performance vehicle due to defective or inappropriate material chosen by Porsche engineers and it may be more common than persons believe. I spoke with an independent repair shop and their Porsche certified mechanics and they indicated that they have conducted five similar repairs due to this defective or inappropriate material and they have recently begun saving the defective parts as they are likewise concerned about the safety of their customers. I plan to pursue this matter with Porsche and I wonder if they have queried their dealers to determine how many replacement parts have been ordered for this problem? This is a liability issue that should be addressed before someone is injured or killed and if Porsche is unwilling to investigate then I would encourage anyone with the same issue to contact NTSB or pursue legal action regarding this defect. I own two other Porsche’s and I have owned a myriad of other cars and I have never seen or heard of failures like these in relatively new cars with low mileage (38,000 in my case). If you would like to join me in addressing this issue with Porsche please respond to my email at jlpoole@tmo.blackberry.net
    Regards to all,


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