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Dreaded Trans Failsafe mode

Posted: Sat Nov 20, 2021 10:42 am
by Si M
Hi Guys,

I'm in a real fix.

My 03 E53 3.0d flashed up the dreaded 'Trans Failsafe Mode' and now won't select a gear after a couple of minutes.
Have tried resetting, but to no avail, and to add to the problem, my OBDII scanner won't communicate with it.

It drove fine up until this, and still does, when it wants to...I am at the end of my tether with it...:(

Any help would be greatly appreciated...

Thanks so much guys

Simon

Dreaded Trans Failsafe mode

Posted: Sat Nov 20, 2021 1:49 pm
by X5Sport
You really need to get it to either a Bosch Autocentre, Main Dealer or other specialist with the right tools. Not all ODB2 scanners will talk to the transmission system controllers. A code read will be needed to help diagnose which part of the system is unhappy.

It sounds temperature related so it’s also worth checking the transmission fluid level and it’s colour whether it smells burnt. If it is very dark and does smell burnt then sadly I suspect that if you are losing drive then the gearbox is about to fail. Low fluid level causes a loss of pressure in the gearbox and that is that, although it jay take a week or two. A torque converter issue can also result in damage. Anything causing pressure loss means the clutches slip, wearing them out quickly. It could be a solenoid as well, but limiting use is key to avoid critical damage that needs a rebuilt box. That comes with a bill of around £2k.

My ‘05 box failed with no warning at all. One minute is was fine and then it sounded like a bag of spanner’s. No warning light either. :cry:

Dreaded Trans Failsafe mode

Posted: Sun Nov 21, 2021 10:46 am
by lezmtaylor
My 2002 4.4 constantly throws this warning if I start the car in Park, so I always start in neutral and do not get '' trans fail safe'' showing.
I did have the auto gearbox oil and filter changed about 3 months ago and it did not cure the problem.

Lez

Dreaded Trans Failsafe mode

Posted: Sun Nov 21, 2021 11:08 pm
by Themoog2
I have just gone through the agro of a full transmission rebuild on my V8...
My symptoms were different - firstly there was a lull followed by an alarming thump when it changed from 3-4.
I found large chunks of metal in the sump but it ran OK for 3 weeks after that service then suddenly lost forward drive.
The trans failsafe warning only flashed up momentarily and then went away.
You state that yours drives fine when it wants to - is the battery OK?
You could do a quick fluid change for circa £30 to see what happens.