Help with CEL P2CEF code

[Rainier]

Got the word that "thermostat stuck" is the issue. Replacement is the fix. Seems they've had a few of these with this issue. ....

Same situation here (US I4). Any further updates from anyone?

I'm hoping this is a bad batch of thermostats (rather than sand in the coolant system ).

 

[gcmak]

Same situation here (US I4). Any further updates from anyone?

I'm hoping this is a bad batch of thermostats (rather than sand in the coolant system ).

how many miles did you have on the car when the error appeared?

 

[Rainier]

how many miles did you have on the car when the error appeared?

Approx 1400 miles, CEL on then automatically turned off after a few start - stop cycles, then fine for a bit and again on and auto cleared itself.

I'm not sure if it just needs to 'settle in' and wont happen again, however dealer will replace (2, upper and lower I think?) thermostats in a few days when parts arrive.

Lotus did not mention anything about sand in the coolant to my dealer.

I did see the video in this thread and find it hard to believe that AMG would still have a sand issue given that the video shows people complaining about it at least 2 years ago in Mercedes cars, but who knows...

 

[Ryan_929]

CEL came back this weekend. I’m taking it back to Lotus on Friday. So far it’s come on 4 times from 100 miles to current 550 miles. Cleared the first 3 and left this last one. I’ll let y'all know what the results are.

 

[yk793]

I read in the FB forum twice from two different I4 owners about the code. Hope it all gets sorted and everyone can enjoy this special car problem free..

 

[MajHall04]

Well add me to the thermostat issue! Car was purchased in December and has 1900 miles. I hope it’s not the sand issue but I suspect it is.

 

[ToonFan]

3 week update. Both thermostats are being replaced. Then another flush and then a "spirited" drive rest and repeat sequence to make sure everything is all good. It's taken a bit to get the parts and go through the process. Fortunately, i have other cars to play with. Note- if you get the check engine light; don't sit on it. Get it scheduled and fixed.

 

[MajHall04]

Well I’m looking at a couple weeks minimum to get my car back….

 

[Rainier]

An update from this owner on their similar/same issue.

Video seemed to refer to this: https://static.nhtsa.gov/odi/tsbs/2024/MC-11000622-0001.pdf

 

[Ryan_929]

Video seemed to refer to this: https://static.nhtsa.gov/odi/tsbs/2024/MC-11000622-0001.pdf

Dropped mine off yesterday for a fix. I shared that video with the service department at Lotus. Hopefully they will actually watch it. They said it should be ready by Monday. I’ll let y’all know the outcome.

 

[Ryan_929]

Well, I just got off the phone with the dealership. They said the thermostat code did not show up on their end. However, there were two new codes. Apparently the aftermarket air filter and aftermarket audio I installed made the ECU go haywire and that was probably the cause for everything. They did a courtesy Ecu flash to make everything communicate again, but they can’t guarantee that will work. They said if the cel comes back on, I have to put everything back to stock.

2 issues with that. The code first came on in a stock setup; and how in the world could upgrading the audio cause a thermostat malfunction?

So it looks like I haven’t gotten anywhere with finding a solution to the original problem.

 

[MajHall04]

Well, I just got off the phone with the dealership. They said the thermostat code did not show up on their end. However, there were two new codes. Apparently the aftermarket air filter and aftermarket audio I installed made the ECU go haywire and that was probably the cause for everything. They did a courtesy Ecu flash to make everything communicate again, but they can’t guarantee that will work. They said if the cel comes back on, I have to put everything back to stock.

2 issues with that. The code first came on in a stock setup; and how in the world could upgrading the audio cause a thermostat malfunction?

So it looks like I haven’t gotten anywhere with finding a solution to the original problem.

Seems weird

 

[MajHall04]

Well I’m looking at a couple weeks minimum to get my car back….

Thermostat parts are local so I should have it back soon

 

[gcmak]

Well, I just got off the phone with the dealership. They said the thermostat code did not show up on their end. However, there were two new codes. Apparently the aftermarket air filter and aftermarket audio I installed made the ECU go haywire and that was probably the cause for everything. They did a courtesy Ecu flash to make everything communicate again, but they can’t guarantee that will work. They said if the cel comes back on, I have to put everything back to stock.

2 issues with that. The code first came on in a stock setup; and how in the world could upgrading the audio cause a thermostat malfunction?

So it looks like I haven’t gotten anywhere with finding a solution to the original problem.

this is the modern dealership way. I won't go as far to say it's all unfounded and unreasonable though. mostly they are tied to 'the book' (including book hours) and a fixed way of diagnosing issues so a dealer who is not willing to be more helpful will always blame the mods first. you can try a different dealer if the error arises again - if that's even a reasonable option for you.