This is my Do It Yourself for the CPS Change. My car is a ML320 V-6
There is some DIY out there but they don't have good pictures and they are for the V-8.


The symptoms were:
1. Engine stalled while accelerating. Car would not re-start.
2. Good Power, no ignition. First I thought it was the fuel pump, Everything sounded strong but no ignition.
3. Was going to tow it home when I decided to try to start engine for the 5th time, it started.
4. Drove it home, checked codes with OBDII Scanner, Code PO335

Decided to replace CPS. It's $150 from dealer (about $50 at AutohausAZ)
MB p/n: a0031532728. Bosch p/n: 0261210171
The part number is different for V-8 and it may be different if you have a different year ML so find out from the dealer before you buy!

Replacing the CPs took about 30 minutes:


TOOLS needed: (see pic)
1. E8 Torx socket. Please get the female, 1/4" drive socket. I had a 3/8" drive and it was too big. I got the 1/4" drive at NAPA for $4. I would'nt recommend using anything else, pls use the torx socket.
2. 1/4" drive extensions. I only needed one, but it is way easier if you have 4 or 5 of the 4" or 6" extensions. If you don't have them, don't buy them just for this job.
3. Socket Wrench.
4. Lots of light.


LOCATION: (see pic)
1. No need to jack vehicle up, no need to remove wheel cover or heat shield, you have a V-6!!!! you are lucky. Look at my pic, find the brake fluid reservoir, I have my ratchet wrench right behind it in an angle toward the engine. Get on top of the engine and put a flashlight right there behind this brake fluid reservoir. It will look like on the other picture I have of the CPS without the plug on it. It will help if you have the new plug in your hand. See the pic of the old and new CPS's.
Once you locate it, the easier way to change this plug is without looking at it. I got on top of the engine and got my whole arm in there. you could get a tall chair and stand on it but it's easier to lay on the engine.

2. Next step is to disconnect the plug. You can feel a little lever/latch that you need to push, that will free the connector, be gentle.

3. Put the E8 socket on the 6" extension and before you put it on the ratchet, put it on the bolt. (see picture of bolt and picture of sensor). Remember, it is way easier to do all this without trying to watch, just trust your hands.

4. Get the ratchet and put it in there. If for some reason you MUST see what you are doing, get more extensions and connect one at a time, to clear the brake fluid reservoir and all the other lines that are around. Now you can get the ratchet at the end and a light to make sure you are turning the bolt the right way : ) Before you loosen it up all the way STOP, tighten it up a little ways and remove all the tools. Then get in there and finish the removal process with your fingers, be sure not to drop it, although chances are it will drop all the way down to the ground.

5. Now you are ready to pull the sensor. All you need to do is put your hand on it and pull it out. Some people had some issues removing the sensor, i wouldn't spray it because that stuff will penetrate the hole, it should come out as long as you are pulling straight out, it will help if you spin it.

6. Once the sensor is removed, plug the hole with a tissue and clean the surrounding area, then unplug the hole and install new CPS. It will be tight but it will go in, just make sure you are pushing it straight down. Remember, it is way easier if you don't try to look at the sensor while you remove/install it.

7. The next step is tricky. the best way to install the bolt is by hand, get in a semi-comfortable position on top of the engine and grab the bolt with your fingers, by now you know exactly where the sensor is, you will be able to feel the hole with your remaining fingers, stick it in there and try to start it. if you cannot start it don't worry. Now grab the socket on and extension and put them on the bolt. AGAIN, if you can do all this without watching, just get your arm in there with the extension and the socket. If you must see it while you tighten the bolt get the socket/ratchet on bolt first and then reach for the extensions. Do not over tighten bolt!

8. Place the CPS plug back on the sensor.

9. Reset code with a OBDII scanner or disconnect battery for 20 minutes (so they say) and reconnect. The code went away by itself on my ML.


Hope this description and the bad pictures help, feel free to add to this thread.

 

I have a V8 and had to remove the fender wall, no need to take the tires off though.

 

Thanks for the tutorial it helped me ALOT! It's pretty cramped in there so I'm not sure how you can do this by eye, I had to feel around to do everything. I have a lot of different 3/8 extensions so I used a 1/4 to 3/8 socket adapter. Disconnecting the plug was a little hard for me. I was being gentle but couldn't get the plug off the sensor. I had to use quite a bit of pressure to get it to click and unlock from the sensor. The new CPS slid in the hole easily. To get the bolt back to mount the sensor in place I did the old trick of taping the bolt to the socket. I then attached the socket/bolt to a short extension which made it easier to feel around and get the bolt into the hole.

 

Thanks a lot Enrike. My wife's ML320 started showing the symptoms described, except that it got to the point it didn't start any more. I ordered the part from Autohauzaz ($40) and used a ten inch extension working from the fron of the engine by feel. The job was not as difficult as getting the securing bolt from the inside of the heat shield after it fell there by accident. Once I put the sensor in the drama was over. The car is up and running for a a whopping $40. Thanks a lot for all the help...

 

Thanks Enrike helpful pics and was so pleased to read I did not have to take the wheel etc off the job went smooth used a 1/4 deep well socket instead of the torx as I did not have the torx

 

I have a question, AutohausAZ has Bosch p/n: 0261210170
Is that compatible in our cars?
When I look up 05 ML350, thats what it lists the part as.

I know for a fact that the part # is 0261210171

 

Thanks for this. The job took 15min. My mother is a very happy person now.

 

Thanks again to this forum, for the easy fix on my CPS, for sure saved me a couple of hundred dollars. Took about 30 min, and I used a puddy inside my socket to keep the bolt from falling and worked like a charm. I did the work from on top of the engine, without an issue. I had both the torx and 1/4" socket and the 1/4" worked best.

Not sure what's going to fail next on my ML but with this forum I'm ready for it.

 

Hi I was reading your thread I have a p0017 code do you think you could help me out?

I need to know where its located is it the same location or one of the sensor up top

The code is P0017 Crankshaft Position - Camshaft Position Correlation (Bank 1 Sensor B)


Thanks for any help on this

 

Thanks for the DIY write up and pictures! I just changed the CPS on my truck and this made it very easy to do.

 

I have a V8 and I'm trying to locate it... Can anyone tell me or have pic. Would greatly appriciate it.

 

They are all on the very back of your engine. Make sure your car is cold before you experiment trying to find it or you will burn your hand. At the very back of your engine half way down you will see a wire connecting , unplug the wire and you will see the CPS sticking into the engine block.

I hope this helps

 

Thanks, I found it and replaced it..... Took me a bit but I got it and it runs great now. Thanks to all for the help

 

Just replaced the CPS today on my 01 ML430, I ordered the part from Bap Geon for $39.95 for Bosch sensor. Being a bigger guy I pulled the tire, wheel well cover and heat shield as suggested. I did not require any access from the top of the engine.

I also used two 1/4" wobble extensions on the torx bolt, easier than the u-joint because they flex and give resistance to push socket on bolt and they perfectly fed through the access I had over the exhaust line. Sensor took literally less than 5 minutes to unbolt, remove, replace and re-bolt, the rest of the time I spent putting the wheel well cover back in. About 30 mins for the entire repair.

I also left the CPS plugged in for removal, made it easier to remove and plugged the new one in before inserting it back in place, didn't have to worry about dropping it.

Biggest pains for me...big hands and not much room..wobble extensions made it much easier.

 

Is the procedure the same for an '05 ML350? I'm having a tough time finding the CPS.

 

It's located on the driver's side engine/ bell housing of the transmission.

 

Zeems it's at the back of the engine above the transmission. You can't see it. You can take off the fire wall on drivers side to see it. You will need extenions to get to it. I jacked up the left side alittle so I could get under and turn on my side to reach up into it. I then could put my hand on it. Hope this helps

 

im trying to do this on 1994 s500 and i can NOT get the dang sensor out!!! anyone have any suggestions?

 

Did you get the bolt out? And if so are you having trouble getting your hands on it to pull it out?

 

Did you get the bolt out? And if so are you having trouble getting your hands on it to pull it out?

 

I got the bolt out with out a problem.... the sensor itself wouldn't budge...I sprayed it w wd40 and got it to twist a bit...but prying broke the top part off the sensor exposing the cylinder shaped magnet inside

 

I'm not trying to scare you but you are in deep trouble if this isn't done right. Don't mangle the sensor any further.

Is there 'straight on' access to the sensor from above?

If there is, pre-soak the sensor with Kano Aerokroil or a 50-50 mixture of transmission oil and acetone. Don't think this stuff will work in 5 mins.

Then purchase a mini slide hammer and with a self tapping screw attached to the head, screw straight into the middle of the sensor and with small easy strokes try and extract the sensor. Small and easy are the key words here.

If there is no availability/access, I don't think you want to know what the fix is.

 

I've heard of a couple involving removing trans bolts and separating the bell from the engine up to dropping the trans.

I'm going to try a puller of sorts.

no there isnt straight on access....I have to bend my arms and hands accordingly


and apologies guys n gals I just realized this is the W163 forum, my bad

 

You have heard right.

 

Well it's now 2013 and I think I have had this problem crop up at 124,000 miles. I had no fault codes. My symtoms were: went for a drive, turned it off, would not start 15 minutes later, turned over very well but no start, also the starter would kind of stay engaged when I let go the key which is typically what you do when you think it going to start. After repeated attempts and another 20 minutes or so it started. However, after about 5 minutes of driving it quit right in the middle of the road. I was able to get over and off the road with my momentum. After walking home and getting a ride back (engine cooling during this time) it started right up and got me home. A few days later I go for a drive with the same results. Having done some research here I changed out the CPS today. The DIY instructions worked great and I was able to find the part and the E8 torx at Orielly's for about $66 total. Went for a drive to warm up the engine and once back in the driveway shut it down. Let it heat soak for a short period and it started right up. I will post if the problem re-occurs in.