- Mercedes-Benz C-Class AMG: How to Replace Crank Shaft Position Sensor
Step by step instructions for do-it-yourself repairs
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How to replace the Crank Position Sensor (CPS) - S500
BACKGROUND
First - I started to notice starting the car when hot took more cranking than normal. Then one day I drove the car 15 minutes and parked it for ~2 hours, only to return to a car which would crank and crank and crank, but not start. After some research on this forum, I ended up purchasing a new CPS which completely resolved my issue. The CPS issue I experienced was also related to heat--eventually (while waiting for the new CPS to arrive) the car got so bad it would die if sat idling in a parking lot for 10 minutes, then would only re-start ~four hours later after all had cooled off.
REQUIRED ITEMS
1) New Bosch Crank Position Sensor (~$40 from autohausaz)

2) E8 female Torx Socket
3) 1/4 ratchet + 8-12in extension
PROCEDURE
1) Remove plastic engine covers (including air filters)
2) Access the CPS from the driver's side - back/bottom of the cylinder head (access pictured below)
3) Remove CPS Plug
4) Remove the CPS
- New and Old CPS ... removed -
Last edited by amac; Jan 12, 2019 at 10:48 AM. Reason: changing image hosting location
BACKGROUND
First - I started to notice starting the car when hot took more cranking than normal. Then one day I drove the car 15 minutes, and parked it for ~2 hours, only to return to a car which would crank and crank and crank, but not start. After some research on this forum, I ended up purchasing a new CPS which completely resolved by issue. The CPS issue I experienced was also related to heat--eventually (while waiting for the new CPS to arrive) the car got so bad it would die if sat idling in a parking lot for 10 minutes, then would only re-start ~four hours later after all had cooled off.
REQUIRED ITEMS
1) New Bosch Crank Position Sensor (~$40 from autohausaz)
2) E8 female Torx Socket
3) 1/4 ratchet + 8-12in extension
PROCEDURE
1) Remove plastic engine cover's (including air filter's)
2) Access the CPS from the drivers side - back / bottom of the cylinder head (access pictured below)

3) Remove CPS Plug

4) Remove the CPS


- New and Old CPS ... removed -

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here's the directory of pics:
http://www.qnorth.net/august/pub/s500_cps_rr/
Last edited by Jud Chapin; Dec 25, 2010 at 11:22 AM.
If you swap it out just start the car after you install the new cps and slowly rev it in park up to 2200rpm and hold it there for 30 seconds and then slowly back down to idle. This will index the cps to the ecu.
www.autohausaz.com has them for 42 bucks on sale
If you swap it out just start the car after you install the new cps and slowly rev it in park up to 2200rpm and hold it there for 30 seconds and then slowly back down to idle. This will index the cps to the ecu.
www.autohausaz.com has them for 42 bucks on sale
I think it just speeds up what the ecu would eventually do anyway.
thanks again.

Mine went out last night (Saturday...go figure
) I bought mine on a Sunday AM at the local Auto Zone...$57.00 out the door.Had to bend the heat/water shield away to get access and put chewing gum in the torx socket to hold the bolt but other than that ...pretty simple.
This is my wife's car and like they say "A happy wife makes for a happy life".










. You have to remove the plastic engine cover.
