Driving this morning I sensed a slight acceleration as I braked prior to a turn and shortly after the brakes applied themselves as I was driving and after idling at a red light it took some RPMs to get the car moving as it felt like the brakes were applied.

I scanned when I got home and got a P0721 Generic Pending Output Speed Sensor Circuit range/performance code.

It's a 2009 ML 350 w/66k miles and I do have a basic warranty sill active, but it covers the major power-train and engine parts.

I do not believe the speed sensors will be covered.

Is this a major repair? Take it to my local MB guy or if this is a bigger issue and falls under the power-train should I take this in to the dealer shop? I have no idea on the possible range of repairs or costs.

Thanks in advance for your feedback.

 

Do you have a 350 Gas, 350 CDI or 350 BlueTec?

Please UPDATE YOUR PROFILE in USER CP to indicate the correct model.

 

It's a 2009 ML 350 4Matic gas.

 

Is the ESP light on?

 

No, no warning lights at all this time. This had previously happened 2 weeks ago, the ABS ESP inoperative lights came on but after sitting for 1-2 days the warnings were gone and the issue did not occur again until yesterday.

The first time when the warnings appeared, it was almost unnoticeable when driving, the brakes did not apply themselves as they were doing yesterday.

 

When the unwanted braking occurs it is a clear indication that there is a problem with the Yaw Rate Sensor.

I do not know what code reader you have, but you need a scanner type reader which can read the codes in every module (approx. 25).

 

Thanks for your time and help.

I have the iCarSoft MB II Scanner and I believe it can scan by module.

I drove it a bit last night no issue and this morning I was on the exact same route as yesterday. On the way there no issue whatsoever but on the way home the exact same issue at oddly the exact same point of the return route. Started with a slight acceleration on it's own, difficulty accelerating from a stop and then the bakes applying themselves.

However this time I did get the warnings lights and message: ABS, ESP Inoperative See Operator's Manual.

Once the warning came on the car did not apply the brakes itself while I was driving but the car did still strain in accelerating from full stops.

 

Then you must read the codes in the ESP Module.

 

Thanks, the ESP scan returned 8 codes:

5116 Right front speed sensor--------check installation position
6002 Supply voltage too high (overvoltage)
6001 Supply voltage too low (undervoltage)
5132 right rear speed sensor-------check wheel bearings
5135 right rear speed sensor-----Implausible wheel speed
5134 right rear speed sensor ----Clean multipole and replace if necessary
7270 Implausible values from RPM sensor rear axle
5399 CAN signal 'Gear Selected' from control unit---N15/3 (etc [EGS] control unit) is implausible

 

Clear all the codes in the ESP and take it for a short drive and see what codes return. Then post those codes.

 

After driving it for several days without issues or codes tonight I noticed when coasting he car accelerated on it's own and then when accelerating from from a stop it felt like brakes were slightly applied. No warning lights or msg appeared on the dash

I scanned and two codes popped up.

Transmission Control Module

0721 Transmission output speed signal implausible when compared to wheel RPM signal

ESP

5399 CAN signal 'Gear Selected' from control unit---N15/3 (etc [EGS] control unit) is implausible


Thanks again for your help.

 

Have you replaced the right rear speed sensor?

See if those initial codes are still stored.

I believe that the 0721 code is being stored because the trans. is recognizing that there is a speed sensor issue, namely the right rear wheel speed sensor.

If the Output Speed Sensor in the trans. was defective, the appropriate code would be stored

 

Thanks for your continued help.

No, I have not had a sensor replaced.

The initial codes are not stored. The only two codes that the car is throwing is 0721 from the transmission and 5399 from ESP.

I drove the car this morning without issue, still no warning lights or message.

It is a big difference cost-wise if this is a simple sensor issue versus the conductor plate.

 

Wait a while and carry your scanner with you. As soon as there is a problem, read all modules but do not shut off the engine.

Or the alternative would be to replace the R/R Wheel Speed Sensor.

 

Thanks for your continued help.

I've driven without issue since my last post over a month ago, and finally tonight the sensor acted up again. I scanned it immediately and got the following codes:

Trans:
D40C --No CAN message was received from control unit N47-5(ESP and BAS control module)(171/203/209) or from control unit N47.5(ESP control unit) (164/219/251/216/221) or from control unit N47.5(ESP,SPS [PML] and BAS control unit) (211/215/220/230) or from control unit Brake system

ESP:
5399 CAN signal 'Gear selected from control unit N15/3(ETC[EGS]control unit is implausible
5136 L6/4 9right rear speed sensor) : Check installation position of sensor
5135 L6/4 (right rear speed sensor) : Implausible wheelspeed
7270 Implausible values from rpm sensor: rear axle

 

You should replace the right rear speed sensor but you will have to supply your full vin # as the correct part # depends on the chassis number.

 

Thank you for all of your help, it seems like a fairly straightforward DIY job.

The VIN is 4JGBB86E99A467683 and looks like the sensor is around $100.

 

Here is the correct part number and also a copy of your DATA Card.

 

Ever get this figured out?

 

Yes, Maj. Dundee was spot on with his diagnosis, it was the right rear speed sensor. Completely resolved the issue.

 

I Have Fault Code 5399 CAN Signal Gear Selected Control Unit N15/3 ETC/EGS Control Unit Is Implausible

Car drives perfect then when hot next day Car in Limp Mode

Any Ideas

 

The first thing you must do is update your profile to include the year, model, is it gas, CDI or Blue and where you live, which tells us you have right or left hand drive.

 

My 2010 R350 has both the ESP and ABS light on. I have read it with a snap on scanner which showed code 5112, 5339(which I believe is a result of 5112) and 0721. It state right front wheel sensor implausible. I have replaced the wheel speed sensor and and the light did not go out. We cleared them after about 3 minutes, it came back on and read the same codes. When I leave from a stop I get a slight ABs bonk sound on the drivers side. The car is sluggish at times and will sometimes not shift out at speed holding no more than 4th. A shutdown and restart seems to solve that. I am trying to determine where to go after this. Wheel bearing is about 1 year old(about 20k miles on it, they usually last around 100k in this car)and seem quiet

 

If one wheel speed sensor goes out, the others aren't far behind.
At least, that's been my experience - MB recommends replacing all 4 corners especially in the wetter climates, there was a TSB or advice given on this issue, I don't have a link for you.

 

As I am showing zero wheel speed on the scanner from the front right, I am going for the bearing today. When this bearing was installed, the mechanic(do not use him anymore) neglected to reinstall the axle nut and we took a good long drive without it, I am wondering if he never replaced the bearing as he said he would when I told him the bearing may have been negatively impacted by the lack of an axle nut(wtf).....I will reply later today.