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Discussion Starter · #1 ·
I have had a very tough couple of weeks with my 2000 528i (100k). The car brokedown, and after multiple start attempts and limping, coughing and sputtering to the side of the road the
transmission failsafe light came on.

I checked the Peak codes after the breakdown and got a cps, precat o2 failures. I replaced these as well as the
ccv valve that was leaking and the dipstick vent hose that had burst. I even changed the plugs, cleaned the throttle body and ivc valve for good measure.

Next I replaced the fuel filter which was original and was plugged (this is the reason for the breakdown - I effectively ran out of gas. Somehow I think the CPS and 02 failures were related to the coughing and sputtering as a result of extremely interrupted gas flow.
I am hoping that the Tranny went into safety mode because of these fault conditions.

I replaced everything started it up and - Transmission Failsafe is still lit - car stuck in 3rd gear. Never even a hint of this problem in the past transmission has shifted beautifully.

One other thing I should mention. I was running without abs controller when this happened as it is in the shop being rebuilt. I as careful to seal everything off so no moisture got into the connector for this module.

Can the Transmission failsafe mode be related to the abs controller not being there?
Or could faulty wheel speed sensors be an issue? It was my understanding that you could run without a controller (of course without abs) and I thought the wheel speed sensors were connected to the abs controller not the transmission control module as well.

I checked the fuses under the passenger cabin filter and they are testing good.

The only thing odd is that I notice a motor or pump running when the motor is shut down. It appears to be the throttle body motor that runs for 15 or so seconds after the car is shutdown. This may be completely normal but I did not notice this be

Does anyone have any suggestions ???
 

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Yes, the TRANS PROG FAILSAFE can be initiated by a number of non-tranny sources (sensor, alternator, etc.) and may not reflect a tranny problem, per se. I suggest that you have the ODB cleared. This will restore you to normal mode. If the default mode recurs, that will indicate your problem is real and still there.

Anecdotal info: My e39 spit the same code on a wet cold day. The dealer spent 2 days attempting a diagnosis and they wanted to replace the tranny (at only 48K). I had them clear the code and reset the OBC. 2.5 years and 25K miles later, the problem never came back. The only good thing is they only charged me one hour labor $115 for reading and clearing the error code.
 

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Discussion Starter · #4 ·
Fixed!

Ok. Here is what finally happened. It turned out to be a MAF unit. I replaced the MAF and trans failsafe is gone, car runs good, shifts like before! CHeck your MAF if this happens to you!
 
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