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2001 325i Sedan
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700 Posts
Discussion Starter · #1 ·
Driving my '01 325i home from Costco, and the Limp Mode indicator came on. Twice I noticed it seemed quite reluctant to downshift. After the second one, the limp mode indicator came on, and the transmission ECU is reporting the following faults:

38 EGS: Symptom, GLUE
31 EGS: Symptom gear monitoring
36 EGS: Gear monitoring 4 (P0734)
41 EGS: Gear monitoring 4 (limp-home program)

I have no clue what any of this means... Could it be just low fluid? Or something worse?
 

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2001 325i Sedan
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700 Posts
Discussion Starter · #3 ·
Already been through all those, and found no explanation of the error codes. And, I've now made it worse by removing the fill plug with the engine off - ~3 quarts of oil came out. So now I need to find some means of pumping it back in plus some, in the hope that the problem is just low fluid.

Before opening the fill plug, I reset the faults, and it seemed to drive ok. All gears were present and accounted for, and it appeared to shift ok, except for being still, at times, reluctant to downshift.

The 6HP25 in our E90 335i started shifting REALLY badly about a year ago. Turned out it was only less than a pint low on fluid, but adding that little bit was enough to get it to behave. These things seem to be REALLY sensitive to fluid level. Luckily I have about 1-1/2 quarts of the correct fluid on-hand. I'm going to re-purpose my Motive brake pressure bleeder into an ATF pressure fluid transfer pump. All I need is a few feet of suitable tubing, and a couple of small hose clamps.
 

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2002 330 Ci
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638 Posts
Already been through all those, and found no explanation of the error codes. And, I've now made it worse by removing the fill plug with the engine off - ~3 quarts of oil came out. So now I need to find some means of pumping it back in plus some, in the hope that the problem is just low fluid.

Before opening the fill plug, I reset the faults, and it seemed to drive ok. All gears were present and accounted for, and it appeared to shift ok, except for being still, at times, reluctant to downshift.

The 6HP25 in our E90 335i started shifting REALLY badly about a year ago. Turned out it was only less than a pint low on fluid, but adding that little bit was enough to get it to behave. These things seem to be REALLY sensitive to fluid level. Luckily I have about 1-1/2 quarts of the correct fluid on-hand. I'm going to re-purpose my Motive brake pressure bleeder into an ATF pressure fluid transfer pump. All I need is a few feet of suitable tubing, and a couple of small hose clamps.
That sucks. Hopefully something simple like low on fluid. Could just be some o rings in the valve body.

I have the same one in my 330ci. Mine is reluctant to up shift. No codes though. I'm going to drain and refill with a new filter and reset adaptations. Maybe rebuild the valve body too.

I have a 6hp21 in my 535i.... same as the 6hp25 with some minor differences. I rebuilt the valve body on that, new solenoids and bridge seals. Shifts so much smoother after that.

Shame there isn't something like xHP for the e46. That's what I use for programming and reading codes on the 6hp21.
 

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2001 325i Sedan
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700 Posts
Discussion Starter · #5 ·
Happily, it appears the problem was just low fluid. I topped it off, and it seems fine now. Odd thing is, I see no indications of leaking, and it's never left a spot on the driveway, so I'm a little confused. I'll keep an eye on it for a while.
 

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2001 325i Sedan
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700 Posts
Discussion Starter · #7 ·
You jinxed me! Limp mode is back. It ran perfectly for quite a while, then started hesitating to downshift for a bit, then went into limp mode. Oddly, this all happened at EXACTLY the same spot on the drive home - a steep, windy 2-lane going up the mountain. Could it be it is still a bit low on fluid? What else could cause this? I have to suspect a possible temperature dependency, given that both times the problem manifested on the only part of the drive that requires the transmission to really work hard at all, and when cold it appears to work perfectly.
 

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2002 330 Ci
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638 Posts
Maybe your bridge seals are going bad. Causing issues with pressure as it works harder and gets hotter. It's a pretty easy job to drop the valve body.
 

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2001 325i Sedan
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700 Posts
Discussion Starter · #9 ·
"Bridge seals"? I assume those are similar to the "mechatronic seals" in the 6HP25, which are plastic "pipes" that carry oil to or from the valve body from above? Drop the valve body, remove old seals, install new seals, re-install valve body?
 

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2002 330 Ci
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638 Posts
"Bridge seals"? I assume those are similar to the "mechatronic seals" in the 6HP25, which are plastic "pipes" that carry oil to or from the valve body from above? Drop the valve body, remove old seals, install new seals, re-install valve body?
Yes.... those things. They are not too expensive. The solenoids on the 5hp are over a grand though. Hope it's none of those.

There's a ton of o rings in the valve body too. I know sonnax makes a kit for the 6hp... I didn't see one for the 5hp.
 

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2001 325i Sedan
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Discussion Starter · #12 ·
Yes.... those things. They are not too expensive. The solenoids on the 5hp are over a grand though. Hope it's none of those.

There's a ton of o rings in the valve body too. I know sonnax makes a kit for the 6hp... I didn't see one for the 5hp.
FCPEuro has a complete rebuild kit for only $145 - all new seals, gaskets, o-rings, etc. to do a rebuild. However, I do NOT want to take the tranny out again. Did that once, and I think I'd likely scrap the car rather than do that again.
 

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2002 330 Ci
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638 Posts
FCPEuro has a complete rebuild kit for only $145 - all new seals, gaskets, o-rings, etc. to do a rebuild. However, I do NOT want to take the tranny out again. Did that once, and I think I'd likely scrap the car rather than do that again.
To do the valve body you don't have to drop the trans. Check 50s kid on you tube. He rebuilds the valve body. He has a whole trans rebuild vid too.
 

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2001 325i Sedan
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700 Posts
Discussion Starter · #15 ·
To do the valve body you don't have to drop the trans. Check 50s kid on you tube. He rebuilds the valve body. He has a whole trans rebuild vid too.
I will look for that. Thanks!

I also have to do a (pre-emptive) mechatronic seal job on my 335i.
 

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2002 330 Ci
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Except it seems to work just fine until it gets hot from working hard.
It's just what happened to me on the e60. They are extremely temperamental if voltage is off even slightly. Turns out my regulator was bad. When I drove hard the gear monitoring codes kept popping. I was really worried because it was a month after I rebuilt the valve body and put all new solenoids too. Anyway, I checked my voltage and it would fluctuate between 10.2 to 15.1. Bad regulator.
 

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2002 330 Ci
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638 Posts
When I rebuilt my valve body. There's a link in there for the step by step for the 6hp

 

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2001 325i Sedan
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700 Posts
Discussion Starter · #19 ·
Is there any way to confirm where the problem is, before tearing into the tranny? I don't mind rebuilding the valve body, but I'd like to KNOW in advance there is a high probability of success. I'd hate to do all that work, and end up right back where I started.
 
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