Mechanics

TRANS FAIL SAFE

1998 BMW 740

Transmission problem
1998 BMW 740 V8 Two Wheel Drive Automatic 11600 miles

Hi. I have a BMW 740iL that has a Trans Fail Safe Mode error message. I had it checked with the OBD tester and it gave me 4 errors. P0720, P0731, P0732, P0734. These are Output Speed Sensor Circuit Malfunction and Gear 1, 2, 4 Ratio Incorrect. Do you know what this may mean? The car does run and moves, but it does not take off very well at all in drive. Once you get up to 35-45 MPH it runs fine. It also goes into reverse fine. Please let me know what you think. Thank you for all of your help. --Alton
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Sgtsturd1
January 9, 2008.



I recommend seeking local professional help. This is a speed sensor issue and will require removal of the oil pan on the transmission
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Dr. Hagerty
Jan 12, 2008.
I have a very similar problem with my 1998 740il (trans in fail safe 4th gear only) and have been told I must get a new trans. Are the speed sensors at the rear wheel hubs? And, I was wondering what the outcome of this person's issue was. I have a solid 1st gear when initialy engaging but immediately goes to failsafe 4th gear.

Tiny
Blake05
Mar 21, 2009.
The speed sensors are inside the transmission.

Dr. Hagerty
Mar 22, 2009.
Replace transmission fluid to solve problems. I have a 98 740il with the same problems. The amsoil brand trans fluid will work fine and is less expensive than the bmw brand. Been driving the car for 2 years since.

Tiny
Hdouglasus
May 26, 2009.

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