[lhuynh336]

So my service department is pretty much BS'ing me, i installed a CSF radiator in my 335xi auto over a year ago, which runs perfectly fine. My shop foreman says I need to do some process so the radiator doesn't flow as good because apparently the radiator in his opinion flows too well and is causing my thermostat to stay opened. Although I've been driving with the radiator for over a year and half with no issues whatsover. He wont parts warranty my 2nd thermostat, could it be a short somewhere? Employee rates are great but they like to just beat around the bush with you and put you on the backburner....maybe I just need to cough up the cash and go to an indy shop.

[feuer]

If radiator flows too well thermostat would tent to stay closed not open in order to maintain engine operating temperature. What makes you think that you have faulty thermostat? Do you have any fault codes? Running cold? Running hot? You info is rather vague. The two wire connector fails often. Deteriorates from oil leaking on it. Check that.

[lhuynh336]

Originally Posted by feuer

If radiator flows too well thermostat would tent to stay closed not open in order to maintain engine operating temperature. What makes you think that you have faulty thermostat? Do you have any fault codes? Running cold? Running hot? You info is rather vague. The two wire connector fails often. Deteriorates from oil leaking on it. Check that.

Yeah fault code saying thermostat is jammed opened even after 2 replacements, i suppose it’s possible i got two bad thermostats. I also can’t tell you about running cold and hot as it’s a 5 minute drive to work and it’s been some very strange weather in NC.

[feuer]

Originally Posted by lhuynh336

Yeah fault code saying thermostat is jammed opened even after 2 replacements, i suppose it’s possible i got two bad thermostats. I also can’t tell you about running cold and hot as it’s a 5 minute drive to work and it’s been some very strange weather in NC.

Is possible but I would be very skeptical that two were defective. I would think that you have something else going on. Check the wire that connects to the thermostat. CFS is know to make engines run on the cold side. Some cars even throw fault code that the coolant system is under-performing.

[GODDSPD]

Same situation here. Had two bad thermostats (I think). The brand I used for the first two was Vemo Q+ from ECS. After replacement I still got the code 2EF4 and car would run cold. It was obvious the thermostats were sticking open.

I let it go for a few months and did some unrelated but major repairs including a replacement engine and I still had the 2EF4 code and cold coolant temps. I even replace the portion of the wiring harness that went to the thermostat.

My last shot is it try a Rein thermostat and throw in a new coolant sensor while i'm at it. If that doesn't work then I have no idea.


What OE brand thermostats were you using?

[feuer]

Originally Posted by GODDSPD

Same situation here. Had two bad thermostats (I think). The brand I used for the first two was Vemo Q+ from ECS. After replacement I still got the code 2EF4 and car would run cold. It was obvious the thermostats were sticking open.
I let it go for a few months and did some unrelated but major repairs including a replacement engine and I still had the 2EF4 code and cold coolant temps. I even replace the portion of the wiring harness that went to the thermostat.
My last shot is it try a Rein thermostat and throw in a new coolant sensor while i'm at it. If that doesn't work then I have no idea.
What OE brand thermostats were you using?

There was BMW SIB for fault code 2ef4. Look up SIB# 12 15 05 where is says to replace the coolant temp. sensor and the engine harness. Might not even be a thermostat issue.

[GODDSPD]

Originally Posted by feuer

There was BMW SIB for fault code 2ef4. Look up SIB# 12 15 05 where is says to replace the coolant temp. sensor and the engine harness. Might not even be a thermostat issue.

Thanks. Ya I saw that, which is why I'm replacing the coolant temp sensor. Although the coolant sensor is working fine so I doubt it's related.

I replaced the portion of the wiring harness that goes to the thermostat and no change. There's no way I'm changing the entire wiring harness. BMW just does that because the techs won't splice wiring.

I'll post up if this rein thermostat or coolant sensor does the job.

[Meatos]

For information, i just changed pump + thermostat, the thermostat was Mahle tm1497. In my opinion mahle is high quality stuff

[lhuynh336]

Originally Posted by GODDSPD

Same situation here. Had two bad thermostats (I think). The brand I used for the first two was Vemo Q+ from ECS. After replacement I still got the code 2EF4 and car would run cold. It was obvious the thermostats were sticking open.

I let it go for a few months and did some unrelated but major repairs including a replacement engine and I still had the 2EF4 code and cold coolant temps. I even replace the portion of the wiring harness that went to the thermostat.

My last shot is it try a Rein thermostat and throw in a new coolant sensor while i'm at it. If that doesn't work then I have no idea.


What OE brand thermostats were you using?

OEM tstats right from my parts dept at the dealer

[Jklad]

Same - Bmw branded tstat and no issies

[lhuynh336]

just to report back. my last resort was to top off the coolant and reset the faults. been a week with no problems.

[GODDSPD]

Originally Posted by lhuynh336

just to report back. my last resort was to top off the coolant and reset the faults. been a week with no problems.

Reset the faults? You mean clear the codes or did you actually reset adaptions?

By no problems do you mean the thermostat is now working as it should, or just that you haven’t seen any cel or codes?

[Alturiak]

Sorry to bring up an old thread, but was there any resolution to the issue? I have the CSF radiator on my E92 AT and within a day of install I got code 348A- thermostat jammed open. I thought "great " my thermostat worked fine before the radiator, but I chalked it up to a possibility/coincidence it failed right after as it was the original with 96k miles on it. I replaced both my water pump and thermostat with new oem/genuine bmw parts today, cleared my codes, and the car still ended up throwing the thermostat code again!

The only thing I have not done is replace the coolant temp sensor (which is working fine), or replace that part of the harness. Any one have any suggestions?

Also how do you do a treatment to the radiator to restrict the flow that was mentioned? Can you elaborate on that as well please?

[juld0zer]

The treatment would be a cardboard or plywood blockoff to impair airflow through it.

A DTC code exists for something to the effect of implausible coolant temp/coolant temp below threshould/engine warmup taking too long etc. This is because of emissions regulations. An engine that is not warmed up is supposed to produce more emissions.

If everything was working properly, the engine should warm up as normal because the thermostat should almost block flow to the radiator. The coolant pump may actually be not turning or only turning very slowly to accelerate the warm up phase). It's not until the thermostat opens (whether naturally or commanded by the characteristic MAP program) that the larger capacity radiator becomes an issue. Because it holds a lot more volume and has more surface area, the heated up coolant is mixed with 'cold' coolant and the DME sees this sudden drop and thinks there is a problem with the thermostat.

I mean.. if you really wanted a new thermostat, the MAP thermostat heating element can fail too

Doea MHD allow for a decrease in water pump flow?

[GODDSPD]

Originally Posted by Alturiak

Sorry to bring up an old thread, but was there any resolution to the issue? I have the CSF radiator on my E92 AT and within a day of install I got code 348A- thermostat jammed open. I thought "great " my thermostat worked fine before the radiator, but I chalked it up to a possibility/coincidence it failed right after as it was the original with 96k miles on it. I replaced both my water pump and thermostat with new oem/genuine bmw parts today, cleared my codes, and the car still ended up throwing the thermostat code again!

The only thing I have not done is replace the coolant temp sensor (which is working fine), or replace that part of the harness. Any one have any suggestions?

Also how do you do a treatment to the radiator to restrict the flow that was mentioned? Can you elaborate on that as well please?

My issue was fixed after doing two things- Going to a rein thermostat (instead of the vemo q+) and replacing my coolant temp sensor (even though it was reading fine).

So either I had two vemo q+ thermostats fail or the coolant temp sensor was the issue. I’m really not sure which one fixed it, but the coolant sensor was very discolored. When we pulled it out it was black then as it started to dry it turned white and chalky. Good luck.

[techwhiz]

Originally Posted by GODDSPD

My issue was fixed after doing two things- Going to a rein thermostat (instead of the vemo q+) and replacing my coolant temp sensor (even though it was reading fine).

So either I had two vemo q+ thermostats fail or the coolant temp sensor was the issue. I’m really not sure which one fixed it, but the coolant sensor was very discolored. When we pulled it out it was black then as it started to dry it turned white and chalky. Good luck.

I have a CSF radiator and on cold days if I don't tool around long enough and get on the freeway, I throw a code.

It only happens on cold days and it's because the CSF has so much more capacity that the car won't heat up fast enough even with the thermostat closed.

[Hernandezj33]

I own a 2006 325i in January of 2019 SES light came on and i got P0128 code (thermostat low coolant temperature). Replaced the thermostat no major issues. Recently while driving back from work SES came back on. Checked the code once i got home and got the P0128 code again. Replaced the thermostat again with in a week SES light came back on. Once again it was the P0128 code. I decided to switch to an OEM thermostat. With in two days the SES light came back on with code 2EF4 (thermostat fault). Cleared the code and it lasted a couple days before the SES light came back on. Once again p0128 code again. Anyone have this issues?

[fatty]

I have a 2008 328xi. I have been getting the 2EF4 code since I bought the car in January of 2019. First I replaced the thermostat with an aftermarket, the code came back. I then replaced the thermostat with a BMW branded thermostat, the code came back. I then replaced the coolant temp sensor, the code came back. I then replaced the radiator with a BMW replacement... the code came back. I have no idea what else to do, besides replace the water pump, but that seems to be working fine. I have noticed that the code comes back quicker in the warmer months for me... and not so quick in the colder winter months. For the love of god, does anyone have an answer for this?

[6Inarowmakesitgo!]

I am having this issue also, 2nd time with the 2EF4 code, cold coolant and oil temps, noticeably increased fuel consumption, fan running more often than expected.

I replaced my tstat last night, and I decided to test coolant/water mix with hydrometer and it was way off from a 50/50 mix; to much water.
I refilled with Pentofrost NF/ filtered water and made it ever so slightly over a 50/50. Coolant temps stay very solid and fluctuate rapidly as different MAP files are selected. Going from cruise, at 103-108c to a demand for power the temps plummet to 82~84c for a run to redline, then jump back up above 100c when cruising again very quickly.
Maybe running a slightly (and I mean very slight~5%) increased glycol level can assist the DME with better temperature regulation? Just spitballing here.

Cause this is my third tstat in 50,000 miles, entire cooling has been replaced (high mileage) and

[Swamp Fox]

Several years later and I am hoping to add to the discussion. I have a 335is with the N54 engine. Last spring I installed a CSF radiator and it was running great (still is) for several thousand miles. Then as the weather turned cooler the 002EF4 code came up. The water pump, thermostat and sensor all have less than 8,000 miles on them since they were replaced. Cleared the code and it came back about a week later. Thinking it might be the DME I sent it off for testing and it passed all test. The 002EF4 code is triggered on cold days after approximately 10 minutes of driving when the engine is almost warmed up.

I am now thinking as someone previous said:
"the thermostat opens (whether naturally or commanded by the characteristic MAP program) that the larger capacity radiator becomes an issue. Because it holds a lot more volume and has more surface area, the heated up coolant is mixed with 'cold' coolant and the DME sees this sudden drop and thinks there is a problem with the thermostat."

Part of the message about the 002EF4 code in ISTA reads:
"the DME compares the characteristic of the measured coolant temperature to the characteristic of a calculated temperature curve. If the measured values and the calculated values deviate too much from each other a fault is entered."

What program (or company that could do a custom tune) is available to reprogram the expected temperature curve so the 002EF4 code is not triggered with a larger radiator?

[Saywhen]

2007 335i. Just got an overheating light on my dash. less than 5k miles ago I had a service engine soon light with code p0128 saying my thermostat wasnt working properly. Replaced it and engine light went away and everything was solid. New coolant, no leaks whatsoever (left splash guard off and checked every day to make sure no leaks). After I did the thermostat and coolant I did the flush thing to burp all the air out, took like 10 mins but again everything was kosher. No idea why its overheating now, with no service engine light, only the over heating light. Any ideas?