BMW Forums : BimmerForums banner

1 - 7 of 7 Posts

·
Registered
Joined
·
16 Posts
Discussion Starter #1
Hello Guys, My LIMP MODE issues has been fixed after week and weeks of research, driving and testing im confident in writing this post to assist my fellow E46 comrades.
To cut a long story short my car suddenly went into limp mode and the following codes came up.

P0721- Output speed sensor/ Wiring
P0731- 1st Gear incorrect ratio
P0732 -2nd Gear incorrect ratio
P0734- 4th Gear incorrect ratio

So I decided to take it to the garage for another opinion and remedy in correcting this issue, after "checking and checking" the garage claims my gearbox needs a rebuild, no in-depth explanation as too what's is going to be done.
Anyway I took my car and parked it back up and started my internet search to fix this problem. I called up BMW and ordered the Turbine Speed Sensor and the Output Speed Sensor as they don't stock these parts, although the diagnosis indicated one sensor was playing up I changed both which makes sense. I got my ATF and gasket from my local indy shop as BMW will be more expensive. ([speak to your dealer to get the correct ATF)
I never done any gearbox work before but was confident in doing this job as I done alot of mechanical work in the pass( I still call myself a (junior mechanic) LMAO.
Got the car on 4 jack stands level, make sure the drain & refill bolts are loosen as you dont want to drain the ATF and then have problems with the refill bolt etc. Now my car has the ZF transmission box, after draining fluids and removing the sump and filter, the Output Speed Sensor was visible and I changed that fairly easy, the Turbine Speed Sensor however was abit more difficult and had to remove the valve body to get to it. Now that the 2 Sensors have been change I fitted back the valve body, new gasket and sump, followed the filling proceeder and that was it really. My car took 6L of ATF, but I guess circumstances vary. My car use when into limp mode after about 15-20 mins driving, its been 1 week now since I done this job and the car drives lovely.

Hope my experience was helpful to you you guys

P.S I did alot of homework and research before I tackled this job, its not for the faint hearted as damage to the valve body could put you into alot of expense.
 

·
Registered
Joined
·
187 Posts
Thats brill mate well done !!
my 323i had the same prob with limp mode and eventually had to put a new gear box in it ,i had the same 2nd and 4th gear ratio codes and unlike you i took the garage's word hence the second hand box at a cost of £300 fitted
so good on you for delving in
 

·
Registered
Joined
·
16 Posts
Discussion Starter #3
Thanks M8, I saved myself a wooping £1600..... all the parts cost me around £300 and my free labour ofcourse ..lol
 

·
Registered
Joined
·
1 Posts
Hello

I'm about to attempt the Limp Mode repair but I have 2 questions,

A - where to get the sensors from

B - is there any steps to follow in order not to affect the car's ECU unit? I assume the battery must be disconnected prior to beginning the "operation"

Please excuse my ignorance and thank you for your help in advance

Regards
 

·
Registered
Joined
·
1 Posts
Hello Guys, My LIMP MODE issues has been fixed after week and weeks of research, driving and testing im confident in writing this post to assist my fellow E46 comrades.
To cut a long story short my car suddenly went into limp mode and the following codes came up.

P0721- Output speed sensor/ Wiring
P0731- 1st Gear incorrect ratio
P0732 -2nd Gear incorrect ratio
P0734- 4th Gear incorrect ratio

So I decided to take it to the garage for another opinion and remedy in correcting this issue, after "checking and checking" the garage claims my gearbox needs a rebuild, no in-depth explanation as too what's is going to be done.
Anyway I took my car and parked it back up and started my internet search to fix this problem. I called up BMW and ordered the Turbine Speed Sensor and the Output Speed Sensor as they don't stock these parts, although the diagnosis indicated one sensor was playing up I changed both which makes sense. I got my ATF and gasket from my local indy shop as BMW will be more expensive. ([speak to your dealer to get the correct ATF)
I never done any gearbox work before but was confident in doing this job as I done alot of mechanical work in the pass( I still call myself a (junior mechanic) LMAO.
Got the car on 4 jack stands level, make sure the drain & refill bolts are loosen as you dont want to drain the ATF and then have problems with the refill bolt etc. Now my car has the ZF transmission box, after draining fluids and removing the sump and filter, the Output Speed Sensor was visible and I changed that fairly easy, the Turbine Speed Sensor however was abit more difficult and had to remove the valve body to get to it. Now that the 2 Sensors have been change I fitted back the valve body, new gasket and sump, followed the filling proceeder and that was it really. My car took 6L of ATF, but I guess circumstances vary. My car use when into limp mode after about 15-20 mins driving, its been 1 week now since I done this job and the car drives lovely.

Hope my experience was helpful to you you guys

P.S I did alot of homework and research before I tackled this job, its not for the faint hearted as damage to the valve body could put you into alot of expense.
Hello Guys, My LIMP MODE issues has been fixed after week and weeks of research, driving and testing im confident in writing this post to assist my fellow E46 comrades.
To cut a long story short my car suddenly went into limp mode and the following codes came up.

P0721- Output speed sensor/ Wiring
P0731- 1st Gear incorrect ratio
P0732 -2nd Gear incorrect ratio
P0734- 4th Gear incorrect ratio

So I decided to take it to the garage for another opinion and remedy in correcting this issue, after "checking and checking" the garage claims my gearbox needs a rebuild, no in-depth explanation as too what's is going to be done.
Anyway I took my car and parked it back up and started my internet search to fix this problem. I called up BMW and ordered the Turbine Speed Sensor and the Output Speed Sensor as they don't stock these parts, although the diagnosis indicated one sensor was playing up I changed both which makes sense. I got my ATF and gasket from my local indy shop as BMW will be more expensive. ([speak to your dealer to get the correct ATF)
I never done any gearbox work before but was confident in doing this job as I done alot of mechanical work in the pass( I still call myself a (junior mechanic) LMAO.
Got the car on 4 jack stands level, make sure the drain & refill bolts are loosen as you dont want to drain the ATF and then have problems with the refill bolt etc. Now my car has the ZF transmission box, after draining fluids and removing the sump and filter, the Output Speed Sensor was visible and I changed that fairly easy, the Turbine Speed Sensor however was abit more difficult and had to remove the valve body to get to it. Now that the 2 Sensors have been change I fitted back the valve body, new gasket and sump, followed the filling proceeder and that was it really. My car took 6L of ATF, but I guess circumstances vary. My car use when into limp mode after about 15-20 mins driving, its been 1 week now since I done this job and the car drives lovely.

Hope my experience was helpful to you you guys

P.S I did alot of homework and research before I tackled this job, its not for the faint hearted as damage to the valve body could put you into alot of expense.
So what cleared code P0734? Was it the turbine speed sensor ?
 

·
Registered
Joined
·
1 Posts
Hi,

I’m pretty new to all this. Have an e46 330ci with a lot of little issues that I’m enjoying learning about.
Currently the most annoying one is the limp mode issue. Sometimes it will come up with the icon but it goes away after restarting the engine. it most commonly comes up if the handbrake is loose enough on a hill to let it rest on Park. Although it has recently been going into limp mode upon starting it on a flat surface which is why I’m a bit more concerned now.

It is not showing any error codes relating to the gearbox, only 2 for “system too lean”.

Could this be an early warning of gearbox issues? I was wondering if I may need to add transmission fluid. After reading up on it I have found there is no way to measure the fluid so I am rather worried about overworking the gearbox if it is a matter of fluid. I’d rather it doesn’t get damaged unnecessarily.

If anyone has any advice, I’d be very grateful :)
 

·
Registered
Joined
·
335 Posts
It's much more likely to be air leaks causing the lean codes, very common on the 330 engines. The big rubber boot behind the airbox is often the cause, or many other rubber pipes or caps in the engine bay. There are several threads detailing how to fix the lean codes.
 
1 - 7 of 7 Posts
Top