Dad's 2006 Phaeton W12 with 6-speed Tiptronic has developed a malfunction the dealer is unable to track down. Going uphill, usually while coasting letting off the gas, the engine will cut out for 1 or two seconds before catching and running normally. No indicator lights come on that indicate the engine has died. This leads me to believe that this event is due to a complete disruption in electrical power. This happens about once or twice a month, often in exactly the same spot when exiting a freeway via an uphill off-ramp. He says the engine once did not catch and the car came to a halt. He could just start it up without any problems and drive off. The dealer found no fault codes and, after close inspection, is stumped. I am suspecting the ignition switch. Other possibilities I am considering include the fuel pump, the ECM, or maybe a problem with the starter disabler/alarm system. I have driven his car a few times since and the engine cut out once for a second or so as he had described in the usual location under the same driving conditions. Dad loves his Phaeton, which has only 55k miles on it, and he'd like to hang on to it. Has anybody here experienced an engine cutting out while coasting or while letting off the gas going uphill?
