What Causes the Abnormal Noise When Accelerating a BMW 7 Series?

1 Answers
LaSophie
07/29/25 8:15pm
BMW 7 Series acceleration with abnormal noise reasons are as follows: Positioning Valve Function Failure: The mechanic used a computer to detect the transmission system, and the fault code displayed 400671 positioning valve function failure. The mechanic explained that this is due to excessive mileage of the transmission, causing wear on the transmission valve body and abnormal oil pressure. When replacing the new transmission fluid, sudden pressure fluctuations triggered this fault. The vehicle's fault is due to abnormal wear on the transmission valve body. Changing the transmission fluid was just a trigger; the actual fault lies in the wear of the transmission valve body, leading to abnormal oil pressure fluctuations. Solution: Lift the vehicle and drain the transmission fluid. Remove the transmission oil pan, separate the transmission valve body from the computer, and upgrade and process the transmission valve body separately.
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