Malfunction Front Right Service Required
Thread Starter
Junior Member
Joined: Nov 2025
Posts: 52
Likes: 15
ML320 CDI W164
Malfunction Front Right Service Required
I am getting this error on the dash along with SRS and CEL. I understand it has something to do with the right front passenger seat. When I had the transmission pan upgrade installed the guy said something was showing high impedance meaning some switch was open. He mentioned seatbelt components. If it was the seat mat sensor that would not say anything about high impedance correct? I am trying to narrow down what to replace.
Super Member
Joined: Oct 2023
Posts: 543
Likes: 191
W221 S500
I am getting this error on the dash along with SRS and CEL. I understand it has something to do with the right front passenger seat. When I had the transmission pan upgrade installed the guy said something was showing high impedance meaning some switch was open. He mentioned seatbelt components. If it was the seat mat sensor that would not say anything about high impedance correct? I am trying to narrow down what to replace.
The SRS light will probably be passenger seat related.
The CEL is on for something totally unrelated and it won't be an airbag.
Thread Starter
Junior Member
Joined: Nov 2025
Posts: 52
Likes: 15
ML320 CDI W164
Scanner
You linked me to the Icarsoft scanner. Will it read fuel systems as well? I smell a little raw diesel under the hood on short drives.
Super Member
Joined: Oct 2023
Posts: 543
Likes: 191
W221 S500
Chances are the rubber lines between the fuel rail, filter and pump are perished. Cheap enough to replace if a bit fiddly for the filter to pump hose. May as well throw a new filter in whilst you're there.
Last edited by AL5461; Feb 22, 2026 at 01:18 PM.
Thread Starter
Junior Member
Joined: Nov 2025
Posts: 52
Likes: 15
ML320 CDI W164
Filter
I was thinking the same thing. Change the lines and filter at the same time. FCP Euro loves me lately as much as I have ordered from them. 🤣
Thread Starter
Junior Member
Joined: Nov 2025
Posts: 52
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ML320 CDI W164
Scanner
I pulled the trigger and ordered the Icarsoft scanner you linked me to. $239 with free shipping.
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Thread Starter
Junior Member
Joined: Nov 2025
Posts: 52
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ML320 CDI W164
Code reading
I am excited to get the SRS and CEL figured out. Kind of feels like a kid at Christmas. 🤣
I am looking at changing the fuel filter and lines as discussed. I see some people run a form of Liquid Molly additive at this time. Have you heard of it? I believe they prime the new filter with it full concentration.
I am looking at changing the fuel filter and lines as discussed. I see some people run a form of Liquid Molly additive at this time. Have you heard of it? I believe they prime the new filter with it full concentration.
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Super Member
Joined: Oct 2023
Posts: 543
Likes: 191
W221 S500
I am excited to get the SRS and CEL figured out. Kind of feels like a kid at Christmas. 🤣
I am looking at changing the fuel filter and lines as discussed. I see some people run a form of Liquid Molly additive at this time. Have you heard of it? I believe they prime the new filter with it full concentration.
I am looking at changing the fuel filter and lines as discussed. I see some people run a form of Liquid Molly additive at this time. Have you heard of it? I believe they prime the new filter with it full concentration.
Ever used it? No.
If you regularly run crap diesel, then it might be worth putting the whole bottle in the tank.
No need to pre fill the filter. Once you've got everything back in place, turn the ignition to position 2 and listen for the pump to stop. Do this three or four times, Double check for leaks and then crank it. Should fire straight up.
Done that every time on both my R350 and ML, both the V6 diesel, with no issues. The system is designed to self purge.😉
Two points worth noting, double check which filter you have before you order it. There's one with a sensor and one without. No difference in how you install them but it helps to start with the correct one to hand. I always use genuine, they're cheap enough and obviously won't give any issues. Likewise the hoses and clamps.
Tother point, be careful as you disconnect the lines as there will be some residual fuel in them. It shouldn't be under much pressure but it goes everywhere and it stinks😂
See what the CEL is on for... It might be fuel related and whilst you're in there and all that😉
Last edited by AL5461; Feb 24, 2026 at 08:13 AM.
Thread Starter
Junior Member
Joined: Nov 2025
Posts: 52
Likes: 15
ML320 CDI W164
Heard of it? Yes.
Ever used it? No.
If you regularly run crap diesel, then it might be worth putting the whole bottle in the tank.
No need to pre fill the filter. Once you've got everything back in place, turn the ignition to position 2 and listen for the pump to stop. Do this three or four times, Double check for leaks and then crank it. Should fire straight up.
Done that every time on both my R350 and ML, both the V6 diesel, with no issues. The system is designed to self purge.😉
Two points worth noting, double check which filter you have before you order it. There's one with a sensor and one without. No difference in how you install them but it helps to start with the correct one to hand. I always use genuine, they're cheap enough and obviously won't give any issues. Likewise the hoses and clamps.
Tother point, be careful as you disconnect the lines as there will be some residual fuel in them. It shouldn't be under much pressure but it goes everywhere and it stinks😂
See what the CEL is on for... It might be fuel related and whilst you're in there and all that😉
Ever used it? No.
If you regularly run crap diesel, then it might be worth putting the whole bottle in the tank.
No need to pre fill the filter. Once you've got everything back in place, turn the ignition to position 2 and listen for the pump to stop. Do this three or four times, Double check for leaks and then crank it. Should fire straight up.
Done that every time on both my R350 and ML, both the V6 diesel, with no issues. The system is designed to self purge.😉
Two points worth noting, double check which filter you have before you order it. There's one with a sensor and one without. No difference in how you install them but it helps to start with the correct one to hand. I always use genuine, they're cheap enough and obviously won't give any issues. Likewise the hoses and clamps.
Tother point, be careful as you disconnect the lines as there will be some residual fuel in them. It shouldn't be under much pressure but it goes everywhere and it stinks😂
See what the CEL is on for... It might be fuel related and whilst you're in there and all that😉
