jackstraw

Hey folks,

I'm pretty frustrated and need some advice. I have a 2008 550i and 52,000 miles. Car has been pretty good to me for the past 6 years with no major problems. So here's the history of the problems that have come up recently.

I noticed a small oil leak. The dealer checked it out when I had it in for the last service under my contract (before the 6 years was up). They said there were two leaks, one from the vacuum and one from the upper left timing case gasket. I took it to my local mechanic who knows BMWs very well and he fixed both leaks. He replaced the vacuum pump assembly, timing cover gasket and valve cover gasket. So all is good. I'm driving the car for a week with no problems. Then one night I'm getting on the freeway and I lose acceleration power and the car goes into limp home mode. No warning lights come on, I'm just restricted to 1500 rpm. I didn't even know the car has this mode, so I pull over and ended up calling AAA for a flatbed tow and took it to the mechanic. He checked all of his work and assured me everything he did was good and this was completely unrelated. He scanned the car for codes and the only one he got was 2D32 -- fault with the Differential Pressure Sensor. He smoke tested the vacuum and no leaks. For good measure, he replaced the hose to the vacuum, he said the o-rings can eventually leak. Anyway, he did that for free. He couldn't find anything else wrong with the car. He reset the fault, test drove it a few times and recommended I pick up the car and try it again. After another day of commuting 20 miles, it went into limp home mode again. I took it back. This time in addition to the pressure sensor fault, there was warnings about DBC Malfunction. The mechanic recommended he replace the pressure sensor. First though, he suggested I take it down the road to another shop, to a friend of his that is a hot shot ex-BMW dealer mechanic and get a 2nd opinion. I did that and he said the same thing... replace that pressure sensor and you'll be good to go. So I had that done, which was costly b/c it's difficult to get to. He showed me the old sensor and it had some corrosion on it and we figured that may have been the problem. The next morning I'm cruising on the freeway and the car goes into limp home mode again!!!!!!! Now it says Engine Malfunction and DBC Malfunction. I take it into him again, he scans it, says there are no errors on the pressure sensor. Now it went into limp home mode b/c it says there's a problem with the actuator motor on the throttle. Basically, the amount I have the gas pedal pressed down differed from the amount the throttle was open. He cleared the codes, opened up the throttle and sprayed some engine cleaner in there and wiped it out, in case the throttle was sticking. We test drove it and it seemed to behave fine. However, last night and this morning it went into limp home mode AGAIN!! Now he is recommending that he replace the throttle body. Ughhhh!!! At least, he says he will do it for free, I just have to pay for the part.

I just don't know what to do. At this rate, I just keep throwing money at it and it's still not fixed. However, I guess when this limp home mode started, I was getting DBC and pressure sensor faults. If the pressure sensor faults went away, maybe I am making progress.

Anyone have similar experiences? Or a wealth of knowledge in this area?

Thanks!

NyC545I

I hear your pain brother, I have a 2009 550i with 55,000 miles and since last summer I've had the check engine light on, it has a misfire, unstable rpm when idling, I unplugged mass air flow sensor and all runs well, I've been taking it to a well known indy repair shop in nyc but, they've changed throttle body, plugs, coils, mass air flow sensor, fuel system cleaning and still I have the same problem as day 1, now I have a antifreeze leak, cant pinpoint it I just smell it, I took off expansion tank but it definitely isn't leaking, no fluid on ground also had to be adding oil every month or soo, not sure if a car with this much milage supposed to be having this issues, I'm thinking about trading it in. At this point I'd rather have reliability over style.

jackstraw

Update on my situation... I went back to my mechanic on Monday and he installed a new throttle body. Fingers crossed.... that seemed to do the trick. Have not gone into limp home mode since.

Might be time for me to sell. Get a new German engineered ride for another 6 years.

nguyendot

They just replaced my throttle body harness for the same issue. Crossing fingers. If throttle body itself fails, i have a replacement for some unknown reason in my garage $400 repair :/

jackstraw

BTW, a new throttle body fixed my problem.

nguyendot

New throttle body harness fixed mine. Next time I'll replace TB myself and see if it fixes it first. Happen to have one sitting around new from when I wanted to get it bored out.