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Discussion Starter · #1 ·
Hey everyone, I've been having a problem with the transmission on my e46 for a while now and i'm at a loss for what to do
specs: 2002 Bmw 325ci, automatic 5 speed

My car has been stuck in this limp mode for a while now and before it would be in limp mode for a little while when i'm first off driving for the day and then if I turn my car off and back on it would be fine. Until one day It stayed on and I couldn't get rid of it, and so the engine light turned on and thought it was just needing a trans flush and filter so I did that but nope. still stuck in limp mode and I attached the codes to what I have wrong. I've been looking everywhere to find where the input speed sensor is and just can't find it anywhere online (location on the trans). I've been also seeing people are swapping Tcms with sort of similar problems i've been having.

(I also wanted to add that another problem i've been having before- When I would full throttle my car from a stop it would seem to slip really bad, and then catch back up, but again now I can't even go anywhere because of how slow it is in limp mode)

So if you guys can help it would be really appreciated.
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Discussion Starter · #5 ·
Find a non-dealer BMW specialist and have him diagnose it.

How many miles ?
It has 155k miles. no rust no anything was kept in garage every winter, so i'm saying it's been really well taken care of. I bought the car last year and he said they already did a trans flush and filter and a flush on everything else. But I wanted to post on here first before going to a specialist, to see if It's something I can do. I'm trying to keep my self involved with this stuff and am trying to learn as i'm 18.
 

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Well before you go to a specialist, you might get a proper code scan of the car's transmission module. It looks like you got a generic "P-code" scan from autozone or similar.

You need a scanner that can read BMW-specific codes. If you intend to keep this car or any similar-vintage BMW, you will want a way to scan your own codes.

But even with a proper scan, I think you are looking at removing your transmission and very likely replacing it. It is occasionally possible to fix a limp-mode situation without replacing transmission, but your symptoms and codes point DON'T point in that direction.

Search on Bali's user guide to setting up BMW coding tools on a laptop.
 

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So if you guys can help it would be really appreciated.
The turbine/input speed sensor is behind the valve body. Valve body needs to be removed to get access. Link below to a project I did a few years ago that will show you it's location.

DIY: ZF 5HP19 transmission: Valve Body

The transmission generally goes into limp mode when there is an electrical fault detected. It won't go into limp mode when it senses slippage. It will shift to another gear and attempt to use other clutch packs. If it goes into limp mode due to major slippages on multiple clutches and it's out of ideas, then it will always start normally once the engine is restarted and then only return to limp mode after it detects the failures again.

If you have an input speed sensor failure that will put it into limp mode the moment it has been detected. If it has been intermittent, I suspect it's not the sensor itself that has failed but some sort of electrical connection issue that is causing a disruption to the signal.

Limp mode by itself feels like major slippage is happening. It's stuck in 4th gear and the TC clutch isn't engaging. It feels like there is a big rubber band between the engine and the wheels. Especially from a standing start where the revs go up and nothing really seems to happen except for a very gentle acceleration. If this is what you are experiencing then I suspect what you think is slippage is just normal limp mode behaviour.

Here's what I suggest:
Disconnect the plug at the transmission and clean all contacts. There are two plugs. One goes to the valve body and the other goes to the switch on the left side of the transmission. I'd clean both but the one at the rear that goes to the valve body is the one that might be creating the issue. Often you can get some oil creep in here over time that creates connection issues.

Buy a BMW K + D CAN cable off ebay and install BMW tools that is available for download here on the forum. Use INPA to look at the transmission control unit and see the errors after initially deleting and then getting the car into limp mode again. This is going to be the first step in diagnosing the issues.
 
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