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sprinkles08, ASE Certified Technician
Category: Transmissions
Satisfied Customers: 22821
Experience:  Chrysler/Dodge/Jeep master tech ASE Master and Advanced Certified, Chrysler/Dodge/Jeep Master Certified, Trans Specialist
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Code 7020 and code 7031 Car will only go in reverse, NO I

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code 7020 and code 7031 Car will only go in reverse
JA: Just to clarify, what's the exact code? And have you tried to reset it?
Customer: NO I have not reset codes. Code 7020 and 7031 Car will only move in 4 and 5 gear and in reverse
JA: What is the model/year of your BMW?
Customer: 1998 740iL
JA: Are you fixing your 740il yourself? What have you tried so far?
Customer: Clean auto trans shift mode switch
JA: Anything else you want the mechanic to know before I connect you?
Customer: Is the auto trans shift mode switch bad or not working
Customer: replied 10 months ago.
how much time be for the question is answered on the 740iL. thanks

hello and welcome to JustAnswer!

I'm assuming the codes ere actually P0720 and P0731. P0720 is for an output speed signal issue and P0731 sets when there is a gear ratio error in first gear. If you've lost forward capability it indicates either geartrain, clutch or hydraulic failure in the trans.

Was it slipping before it stopped moving altogether?

Customer: replied 10 months ago.
I spilt some lemonade on the auto transmission shift mode switch. The switch is for the automatic mode or manual mode which is located next to the shift lever on the council. I took the switch apart and it looks like it was shorted. If I replace the switch will that eliminate the codes.

That wouldn't have an affect on speed sensor or gear ratio error codes.

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