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Steve, BMW Expert
Category: BMW
Satisfied Customers: 25412
Experience:  BMW Expert
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My e39 525i auto has come up with a transmission fail safe

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Hi, my e39 525i auto has come up with a transmission fail safe alarm. I called the AA they cleared faults.PO344 unknown and PO705 gear sensor but the faults back. Any ideas guys I was going to add more transmission fluid asit looks low

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.the codes indicate an issue with the transmission position sensor. if the fluid is low, it will not hurt to top it up, but it will not likely resolve your issue. You will likely need to have a new position sensor fitted, however I would recommend a proper diagnostic with an actual BMW scan tool as opposed to a generic p code reader to confirm.


Please let me know if you have further questions. Please do not forget to click a positive rating as this is the only way I receive credit for my answer, thank you. Best wishes with your vehicle.

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Customer: replied 1 year ago.
Thanks Steve the cars in limp home mode so if I replace the position sensor and top up the transmission fluid will it clear the fail safe alarm so I can take it to a garage.
Also gave you 5 star rating thank you

it should when all info is taken at face value, but the reason I suggested a proper diagnostic is because using generic P codes can sometimes be misleading. you should also replace your cam position sensors - that is the 344 code.

Customer: replied 1 year ago.
I'll have that bmw diagnostic done then and take it from there.
Thank you