p0720 output speed sensor error..
 

Hey guys,

My car was having some shaking and engine dying issues for a while especially under load (driving) coming down to lower rpms. I blamed the intake and changed almost every part of it including the MAF. The car was not smooth shifting down to low gears, it would either shake or recover almost dying off. Well, it gave me the P0720 error yesterday and we are on TRANS FAIL SAFE mode now.

From what I read this usually is a sensor issue (hopefully not the whole transmission since its not that old, this is my second transmission at it only has 40k miles on it).

What do you guys think, is there DIY for this?

Thanks for all the help..

Oz

X5 2001 4.4 (at 160k miles)

Difficult question? Anybody? Nobody had this problem before?

Any help would be really appreciated..

Ozzie

In my experience with the 5HP24 transmission speed sensor errors are indicative of deeper issues but the sensors (output speed sensor in your case) are relatively cheap and simple to replace so you might want to try that first? The BMW part no. is 24341218551. You just need to drain the fluid & drop the sump pan – the sensor is held in by a single Torx T27 screw & bracket.

http://i260.photobucket.com/albums/i...rearsensor.jpg


If you measure the resistance across the terminals it should read between 285 & 365 ohms.

http://i260.photobucket.com/albums/i...Resistance.jpg

Phil

Thanks for the great info. What kind of issues did you have to deal with? I have a feeling that I am doomed to go for my 3rd transmission and if thats the case my X5 will be a trade in for a new one..

Thanks again,

Ozzie

Was the torque converter replaced both times when you had your transmission changed? The symptoms you describe sound similar to what you would expect to feel if the torque converter lock up clutch were failing to disengage properly.

Phil

Hey Phil,

I am not sure if the torque converter was changed. What's happening right now is the Reverse gear is actually working (which wasnt two days ago) and no movement when I put on forward, I step on the gas a little, the car jumps forwards then the error 0720 pops and TRANS FAIL SAFE mode of course.

I will drive the car in that mode to my mechanic tomorrow to see what they are going to say..

Thanks again,

Ozzie

Hmmm, that sounds more serious than just a speed sensor problem. Does the transmission behave itself better when cold and get worse as it warms up?

Phil

Could be, before it came to this point (p 0720 error and TRANS FAIL SAFE), my car actually would shift not as smooth after the engine heat up (I mean heat up after at least half hour of stop-go driving, but not overheat) but I always blamed other parts (like emission for that).

Oz

The reason I ask is that I often get 5HP24s to repair where the transmission behaves normally after starting from cold but then after around 20 minutes (which is how long it takes for the transmission fluid to get up to temperature) the transmission failsafe message appears & the transmission goes into limp-home mode (4th gear + open converter). On cooling down again, normal operation is restored.

This is invariably linked to a seal leakage problem. When the fluid is cold and viscous the leakage is small enough that the pump flow is sufficient to maintain pressure on the particular clutch. Once the fluid warms up and the leakage increases the pump cannot maintain pressure and the clutch slips. The ECU detects the slippage via the two speed sensors and drops into failsafe.

Similarly, if the transmission fails to engage either Reverse (C & F clutch) or Drive (A clutch) at tickover, but then slams the clutch(es) on when the engine revs are increased, this could also indicate that the additional pump flow produced by increasing the engine speed was overcoming a seal leakage problem.

Phil

Well my mechanic had bad news for me. He said the sensors were ok and the torque converter was gone, so my transmission would need rebuilding.
They are asking for $3k for everything, I guess it's a good deal, I will probably go for it..

Thanks again for all the help..

Ozzie

My problem is that i get the P0720, 1746, and 0715 codes like clockwork after heavy rains. Any other times its completely fine, shifts good, everything. Any chance the computer for the trans is just getting wet? It's happening to me as we speak AFTER the car has sat outside in the rain after working for 8hrs this evening. Problem is...I STILL havent tried to find the computer to see if thats the issue.

Yeah, Mine started with Failsafe in rainy days. Afterwords, it got failsafe from the start and a big slam into 5th gear from the start.(sometimes Manual would work) afterwords, Driveshaft or something like that was detected broken. had to rebuild.

GREAT REPLY PERFECT ANSWER!
 

PRO!

@ RRPHIL
 

my dsc module crapped out the other day but it causing my cluster gauges to go bananas... ie: no rpm or speedo and temp gauge redlining and returning to normal...
when i disconnected the dsc module the cluster returns to normal.
rpm comes back and speedo and normal temp.

i assumed it was the module and sent it out the shop says in unrepairable after feeding me a bunch of lies on how they were working on it then tell me under a scope 2 days later its damaged...thats a whole dif story im sending the unit for a second opinion...

my question to you is you describe my tranny symtoms to a t and i prepared for this day...i changed the filter and fluid only in the pan and it bought me 20k im currently at 148k miles.

it seems like its warming up then the a disc slips could this be anything in junction with the dsc module? is the tranny module on the same circuit and could it be the cause of the dsc unit shorting my cluster?

im wondering if its just the tranny since i know the tranny has been crapping.
but could it be the dsc unit too and at the same moment the tranny dies?

it is a bmw i guess lol

but i wonder if my abs module is bad at all is the tranny ecu on the same canbus as abs module?

any help is greatly appreciated!