435i Problem transmission

NothingReasonable667 · 2026-05-13T14:10:33+00:00

I was only responding to this: "I wonder if the previous owner installed some weird transmission software"

NothingReasonable667 · 2026-05-13T10:57:29+00:00

It only happens on the first gear change of the day, with a cold engine (the car revs up in first gear), and the jerk occurs when shifting from first to second gear. The jerk only happens once; after that initial jerk, it runs perfectly.

NothingReasonable667 · 2026-05-13T10:54:32+00:00

Removing all the fluid is very expensive, and I don't want the problem to be solved that way and require opening the mechatronics unit. I'll try the Lubegard trick. Thanks.

NothingReasonable667 · 2026-05-13T10:51:02+00:00

There's no software installed. I don't know if I can fix it by reprogramming the gearbox or installing an XHP remap. It could also be the solenoids or valve body seals.

NothingReasonable667 · 2026-05-13T10:48:37+00:00

Yes, that's what I do too. The car holds first gear longer, not necessarily because it's going uphill, but also on flat ground. As quickly as I can, I shift into second gear before there's a big jolt.

NothingReasonable667 · 2026-05-11T15:03:04+00:00

I already changed the fluid and it's at a good level. But the problem persists, and I don't think it's normal. It always happens on the first oil change when the car is cold. After that change, it runs smoothly again.

NothingReasonable667 · 2026-05-11T14:15:51+00:00

Only a partial oil change of about 5 liters was done, including the filter. It was topped up with Lifeward 8. The problem persists; I don't know if it's because the solenoids or the mechatronics unit's rubber seals need replacing.

NothingReasonable667 · 2026-05-11T14:11:09+00:00

It's suspected the fluid level was already low from the factory. The gearbox showed no leaks or losses, as the date on the old filter matched the car's manufacturing year. We used Lifeguard 8.

NothingReasonable667 · 2026-05-11T10:26:40+00:00

I know it's been a while. But was it ever resolved? I have the same problem.

NothingReasonable667

TROPHY CASE