MBWorld.org Forums - 2002 CL230 - Thermostat Replacement (P0128 Code)

Thermostat was found to be the problem after I noticed the temperature would always be around 70/80 degrees and I had a P0128 code on the scanner.

When searching for the location of my thermostat there were not many pictures available so I decided to take one to aid others.

https://cimg0.ibsrv.net/gimg/www.mbw...9a9086a41e.png

The following is a step by step on how I c/out the job. The replacement took roughly 2 hours (in the Canadian winter).

1. The first step is not necessary however I found that removing the airbox (one bolt and a clamp on the R/H side and then pull as there are 3 lugs that fit inside rubber grommets) helped in removing the thermostat as it provided more flexibility for the hose as the thermostat was stuck. With airbox installed the hose does not have much room to move due to a retaining clip (orange arrow in picture).

2. The next step is to remove the large engine cover (6 bolts) from underneath the car to gain access to the coolant drain (red cap).

https://cimg0.ibsrv.net/gimg/www.mbw...c51db45193.png

3. Next step is to drain some of the coolant from the system by opening the red cap slightly. do not remove the cap fully as you will drain more fluid that is required, I drained around 1.5 litres from the system.

4. Once the above steps have been c/out, you can then remove the clamp from the hose and the 3 bolts from the thermostat (red arrow). If you still have some coolant leakage then drain more coolant from the system. Once the thermostat is free from where it mounts you can then carefully release it from the hose. Like I said earlier on in the post, my thermostat was stuck to the hose so I slowly worked my way around the hose with a small flat blade screwdriver taking care as to not damage the hose.

For installation of the new thermostat, do the above mentioned tasks in the reverse order.

Once the installation is complete, top up the coolant with the amount that was removed then check for leaks.

Thermostat was purchased from @autopartsway.ca and came with the seal.