Help with CEL P2CEF code

[Ryan_929]

just to add my own experience, I bought my car new with 17 miles on it, picked it up a month ago, I believe my car was built around sept 2024 or later.

P2CEF came on around 975 miles on the odo, started the car up and didn't even make it out a block. I was literally taking the car out to finish the 1000 mile break-in. I cleared the code. It has not come back since, I've driven roughly 200miles on it so far. I hope it's a VERY small amount of sand and is just stuck somewhere now and doesn't restrict any flow or get my thermostats stuck.... I can live with it just being stuck somewhere and not flowing around.... I really don't want to have to take it in to the dealer to let them take 2 months to diagnose or have to do a full flush in attempt to get the sand out.

Or even better, hope it was just a fluke, but i doubt it.

If it does come back on, and you have to take it in, I would suggest printing up the Mercedes TSB on the issue and make sure the advisor gets it to the service tech. Mine sat for almost two weeks before they came up with a diagnosis. My part was ordered and received within two weeks. I had the car back the following day so hopefully you’re not looking at a several months experience.

 

[gcmak]

Saw this owner drop another update to their case:

 

[Rainier]

I was happy with the District rep from Lotus. I felt very at ease as he stated he would do what it takes to make it right even extend the warranty.

Did you receive an extended warranty?

 

[MajHall04]

Did you receive an extended warranty?

No but I will ask one this time around if I don’t lemon it.

 

[Rainier]

Does anyone have a diagram of the I4 coolant system that they could post here?

I'm trying to get a full picture of all the components involved—radiator, turbocharger heat exchanger, heater core, water pump, etc.

 

[Neil D.]

Are you all 100% sure that P2CEF is related to a sand left in the casting issue ?

 

[MajHall04]

Are you all 100% sure that P2CEF is related to a sand left in the casting issue ?

Yes. It’s been a MB issue for years. There are photo of thermostats pulled out showing the grit in the thermostat. Now, the deals just keeps saying stuck open and hasn’t shown me my thermostat but all indications point to casting issues. I heard it was resolved in Dec 2024 with the new casting process.

 

[Neil D.]

Yes. It’s been a MB issue for years. There are photo of thermostats pulled out showing the grit in the thermostat. Now, the deals just keeps saying stuck open and hasn’t shown me my thermostat but all indications point to casting issues. I heard it was resolved in Dec 2024 with the new casting process.

Thanks for your reply, no hard evidence in a Mercedes powered Emira. You could also assume a bunch of faulty thermostats. From what I see in this thread, there is no confirmed fix, with at least 1000 miles and no engine light. Could be chasing windmills.
Neil

 

[Rainier]

Thanks for your reply, no hard evidence in a Mercedes powered Emira. You could also assume a bunch of faulty thermostats. From what I see in this thread, there is no confirmed fix, with at least 1000 miles and no engine light. Could be chasing windmills.
Neil

Yes their is evidence of debris in the I4.

My I4 had a few grains or flakes of debris found in the thermostat; my dealer found a lot more debris in another I4.

https://static.nhtsa.gov/odi/tsbs/2025/MC-11013331-0001.pdf

 

[MajHall04]

I’m on failure two. I may just lemon it.