Hi,
I have a W211 E220 CDI 2004 model. My car has started to have intermittent "failure to start" problem. It can happen at any time of the day. For example, yesterday morning my car started on first crank but during the day, i stopped at a shopping plaza for 10 minutes and when I got back, the car failed to start. I cranked it a couple of times and it did not start after going through the complete cranking cycle. Finally, i waited for a few minutes, cranked the car again and it started in half a second without problem. This issue can happen at any time during the day and it does not matter how many miles i have driven during the day.
What could be the possible issue? I have replaced the glow plugs recently and they are working fine.
Help!!!!

 

Do you have any codes (is the check engine light on)?

Sounds like crankshaft position sensor, which I assume diesels have as well as gassers. Anyway, at least in gas models, classic CPS failure signs are intermittent failures to start when the car is at operating temperature. Once the car cools some, it may start right up.

 

There was a error code once for CPS, but i cleared it and it didnt come again. Also, the intermittent starting problem also happens sometimes when engine is cool

 

Okay the same thing happened to me awhile ago and although you are probably thinking I am going to tell you what I did to fix it (I want to) but at that time it was multiple things at once. But what I CAN tell you for sure is that what you just described is exactly what I experienced. It really does seem to be more likely if the car is left undisturbed and essentially "cold" but later inexplicably it will turn on as if nothing was wrong. Here is what I remember i did but first and foremost prepare yourself because if you dont get this sorted out really really soon its a matter of days before your car simply wont start up at all, which is what happened to me.

Anyway, change the CPS even if the code went away, change it out you have to rule that out first, its cheap and a quick repair if you use the right tools.While replacing, make sure to use smaller sized sockets with extensions. I remember I went hours trying to bolt the sensor back on using a 3/8 sized socket when the same sized socket at 1/4 size was the only way to get it to work. Problem is that your hands cant see what how much space you have to work since you cant see when your hands are halfway into the engine bay near the firewall. Use the 1/4" ratchet.

If you still get the same no start issues after replacing the sensor, take a careful look at your shifter, there is a good DIY thread someone recently brought back to life that is excellent. If the car doesn't know what gear its in or if you cant shift from park past neutral into drive or vic versa,you might need to replace or look for cracked solder joints as the aforementioned thread explains very well. The sometimes no start without a real cause and effect correlation alludes to an electrical problem where sometimes it makes a connection allowing you to start and sometimes it doesnt. Replace the crank position sensor then consider replacing the shifter. From what I remember that was what I did to remedy the issue. The shifter is plug and play and can be be had used for a little less than $100 on eBay.

 

I had a CPS problem as well, but it was only intermittent at first. It was code P0335, and I cleared it. Then I had a hard start again, it went away, came back again, then cleared it, over and over, etc. It sounds like you have a CPS problem. I changed the CPS with a Bosch sensor and problem solved, but note I used a cheaper sensor from Advance Auto (because it was in stock) and the sensor did not work. If you change the CPS get the Bosch or OEM..

 

I had a similar issue on my car last year. Changed the CPS sensor myself, its not difficult and with proper ratchet (you would require a ratchet extension though). As stated above, buy a good quality Bosch or OEM CPS and you should be fine.