Transmission Fault code P0741

[stewart thornton]

Hi 

New to the club having moved to France from the UK. Having just changed the  tranny oil on my 2005 E46 a fault code P0741 has come up which I gather is the TC lock up clutch. Can anybody tell where the solenoid is located for the TC clutch so that I can check to see if it is working correctly. The car runs fine but obviously the lock is not working correctly.

Thanks in advance

 

[Greydog]

Hi Stewart

Welcome to the Forum

When you changed the Transmission Fluid did you use the correct Fluid and are the levels correct ? If memory serves your box is ZF 6 speed, and should use ZF Longlife Fluid.

The Lock up clutch for the TC is inside the TC and friction operated so if there is an issue there it is a box out job then either rebuilt or new TC

Dave

[stewart thornton]

Hi Dave,

Thanks for getting back. Correct fluid and levels. The error message only came on after the fluid change and I am just wondering if the clean fluid has dislodged some debris and has jammed the valve. Is the solenoid and valve accessible after the tranny sump has been removed or is it external?. I intend to change the oil again to see if it helps.

Stewart

[Greydog]

Morning Stewart 

I don't know how much you know about the auto boxes, so don't want to sound like "teaching Granny to suck eggs" the mechatronic valve body inside the box only controls gear changes, the torque converter has its own internal centrifugal pump and clutches including the lock up. 

Fluid changes often don't clear the fluid in the TC it either takes specialist equipment to flush the TC or sometimes 2 or three fluid changes. However if there is a fault with the lock up clutch in the TC the as far as I know the only fix is a new/replacement TC. How does the car drive ? Have you tried clearing down the fault to see if it re-occurs 

Dave

[stewart thornton]

Hi Dave,

Changed the fluid and filter which was really dirty. The fault code only appeared after the fluid change and only appears on the Autel diagnostic tool with nothing on the dash. I am wondering if the valve has some debris and is it accessible with the sump pan removed or is it an electrical fault. The tranny is smooth with no over revving and everything is fine. I have cleared the fault but it has come back. Weather in France is lovely.

 

Stewart

[Greydog]

Morning Stewart

Take a look at the Diagram below, the torque converter is large piece in the Bell Housing at the engine end in the blue section and as you can see not accessible from the sump. The torque converter lock up clutch is mechanical not electronic. It is in effect doing the job of the Clutch in a Manual car and is separate from the gearbox

Back to my question "how does the car drive?" if it drives OK I would be inclined to try a tube of DR Tranny it really does help in some cases. Then clear the fault run it for a few miles and check and clear it again if necessary. To be sure of the issue you need a BMW specific diagnostic reader, Autel are great (I have 2) but for BMW a specific reader will gives so much more information, example my BMW 1.4.0 can identify which parking sensor is not working and whether it is the sensor or wiring, Autel wouldn't know I have Parking sensors let alone which one was faulty.

On an old laptop I have programs for Volvo, Mercedes, BMW, and Subaru the most expensive was the Volvo software at £70 The Autel units I use on other makes Peugeot, french poo, Toyota etc owned by friends (mainly our sons) and neighbours. 

http://x-engineer.org/wp-content/uploads/2017/02/Automatic-transmission-with-torque-converter.jpg?8a0af4&8a0af4

So if the car is driving OK changes are smooth no clonks snatches or lurches going up and down the box then I would try Dr Tranny in the first instance.

Changing filters and fluids will never fix a mechanical issue (worn clutches etc) an additive like Dr Tranny can help the torque converter extend it's life but again can't fix a worn out or damaged clutch. Torque converters are sealed unit, working on them requires them to be cut open rebuilt and welded back together so are not something for the home mechanic. Access to the Torque converter requires the box to be removed then the Torque converter can be removed (Note. The Torque converter holds a fair amount of transmission fluid so if you don't want a mess have a tub ready) 

Dave

[stewart thornton]

Hi Dave,

My question is there a solenoid operated valve that directs fluid to engage the TC lock up clutch, and if so its location.

Regards

 

Stewart

[Greydog]

No as said previously the Torque converter is independent. Attached is a service manual for your ZF 5HP-19 gearbox showing all solenoids and their operation and her is a Youtube link to the Torque converter and what's inside it (

 

Dave

ZF 5HP 19 manual.pdf

[stewart thornton]

Thanks Dave,

You have been brilliant and thanks for taking the time to reply. Hope all is well in the UK

Stewart

[Greydog]

You are welcome Stewart 

I would try a tube of Dr Tranny in your beasty not normally a promotor of "snake oil" type fixes but this is one that works, 2 of the 5 series touring that my brother inlaw has owned (same box) had persistent TC Lock up faults. BMW Dealer tried the "New Gearbox" route, a Specialist suggested a new Torque Converter a still expensive a tube of Dr Tranny as an experiment fixed the first one it took about two weeks to work into the system then fault cleared and never returned. When the fault came up on the second car we just stuck a tube in same result. Hopefully it will work for you. 

Yes all good here not difficult to social distance when yo walk with 5 dogs and Majestic Wine are still delivering so the essentials are all covered 🤣

Dave

[stewart thornton]

Hi Dave,

Who stocks this in the UK? Having just changed the Headlights to left hand drive to get the car through its Mot the bulb failure warning light on the dash has come on. Any ideas on how to turn it off. Living in France has many advantages, cheap wine and open space which our rescue German Shepherd just loves.

Stewart

[Greydog]

Hi Stewart

There are several Transmission specialists who sell it Try Google or Ebay you should be able to get even in deepest darkest France 🤣

Try the old Battery disconnect trick see if that resets the Light Check or it may be that it needs resetting in the ZKE you will need a Diagnostic program or someone with one to do that.

Dave