[Inter Alia]

I have a 2007 328i coupe. My new BMW has arrived, so it's time to get rid of my old one. Rather than selling it on Vroom, I'm considering posting it on here.

But I'm wondering whether a mechanical issue is likely serious or not.

For a year or so, the transmission light has come on and off. Car has run the entire time, even when the transmission light is on.

When this first started, the warning light rarely came on. When it did come on, I would turn the car off and the warning would go away and stay away. Then weeks later it would come back on again, which I could get rid of by restarting the car.

Then at some point, the light came on and wouldn't go away. I still drove the car, but it had less power under 25 mph or so. After that does, acceleration and power were normal.

At this stage, I knew I was getting a new BMW, so I didn't want to invest in fixing this. A non BMW mechanic said they'd have to spend time to figure out the issue and said it wasn't worth investigating. Instead, they recommended I change the transmission fluid (around 97k miles at that point) to see if that quickly and cheaply fixed the issue.

I did so, and the transmission issue went away for months. After some extended freeway driving, it came back on one day and hasn't gone away. The car still drives, but less power under 25 mph.

On top of this, I have oil leaks, but again, with my new BMW coming in, I didn't want to fix those either (because the same mechanic said they couldn't tell if the leaks were easily accessible or hard to get to).

I've been told this might not be a serious, expensive issue to fix. Or maybe it is. I lack the expertise to even begin to diagnose the matter.

I'm wondering whether it is worth having someone look at it to potentially fix it for cheap and sell the car for more, or just get a couple thousand from Vroom, even with the transmission light on.

I took good care of the car, and don't see why it can't last another 100k miles, if the transmission isn't actually shot. My understanding is that transmission issues at this mileage are out of the ordinary.

Thank you for any advice.

[CTinline-six]

A few things:

1. Sounds like you need a new mechanic, since this one doesn't seem to like diagnosing anything or giving substantial answers.

2. You'll definitely get less money for the car with a transmission warning light on the dash regardless of what is wrong with it.

3. If you are able to post the BMW specific trouble-code that is being triggered (any BMW shop can find out the code) then everyone here can give you a better idea of what could be wrong.

[Inter Alia]

Thank you, both! I'm going to take the car to my original mechanic, and forum legend, Long Tran. The last mechanic who gave me little info was a random shop. I'll report back with a diagnosis from LT.

[Inter Alia]

The transmission error code is 004f8d.

[F31B48]

Originally Posted by Inter Alia

The transmission error code is 004f8d.

That code means the trans is slipping between gears 5 and 4. It could be as simple as low oil level in the trans. Is there any transmission oil leaks?

I have had the same fault code before on my 330i. I changed the transmission fluid and mechatronics seals (used genuine parts and fluid) Haven't had an issue since.

[mehrlovin]

I had the exact same slippage at higher speeds and followed FCP Euro's kit on this. I had a mechanic come over to my house and did the following which resolved it totally.

1) Removed and clean transmission pan
2) Replace transmission fluid with Redline racing trans fluid.
3) Replace mechatronics seal
4) Replace transmission fluid filter

Its been fantastic ever since. 30k miles onward.