11 335i N55 throwing 348A code. Thermostat?

wtobiason · 11-28-2016, 04:21 PM

I was driving to work today and lost all power. I could maintain speed but no acceleration. The cooling fan was on high too. I contacted Burger tuning with the code my JB4 gave me and they said it was "348A is a thermostat jammed open code"

What could be causing this? Is the thermostat dead or is there somehting else that might be causing this?

Thanks all for your input.

Peen · 11-28-2016, 04:22 PM

Happened to me when water pump went out. Check for coolant under car? Also check for coolant in reservoir.

JETmn · 11-29-2016, 07:32 AM

Normally replace both the t-stat and water pump at the same time since they are right next to each other and both are prone to failure. Then you should be good for another 50k+ miles.

Euroboost91 · 11-29-2016, 09:58 AM

My car had the same issue and it turns out the waterpump failed, most likely the same in your case.

TeinBMW · 11-29-2016, 11:52 AM

Change out the water pump and thermostat....you can keep driving it but the codes will keep coming up until your car fails. Advice: get them replaced ASAP to avoid further engine damage.

wtobiason · 11-29-2016, 06:52 PM

Has anyone else had this happen and the car had very little power without the CEL coming on?

OneMoreAlex · 11-30-2016, 07:22 PM

Quote:

Originally Posted by wtobiason

Has anyone else had this happen and the car had very little power without the CEL coming on?

Sounds like the car went into low power mode. If you have the JB4 set on 1/3 you won't get the CEL light to come on. Disable autoclear with command 1/4.

Like others have said your water pump is probably on it's way out. I'd get it checked asap. The same thing happened to me and the car left me stranded on the side of the highway waiting 5 hours for a tow truck.

wtobiason · 12-01-2016, 08:38 AM

I do have the JB4 auto clear DME disabled and didn't get a code. I checked the code 1/1 and got 348A. Weird.

It's going in the shop to change the thermostat. My shop recommended waiting for the water pump seeing how I have 62k miles.

wtobiason · 12-01-2016, 08:41 AM

Quote:

Originally Posted by Euroboost91

My car had the same issue and it turns out the waterpump failed, most likely the same in your case.

Did yours come up with the thermostat stuck open code?

MadToy · 12-03-2016, 05:21 PM

Quote:

Originally Posted by wtobiason

I do have the JB4 auto clear DME disabled and didn't get a code. I checked the code 1/1 and got 348A. Weird.

It's going in the shop to change the thermostat. My shop recommended waiting for the water pump seeing how I have 62k miles.

62k is about the time the water pump fails. Change both, since it's the same amount of labor.

DunklerEngelVNV · 12-04-2016, 05:49 PM

Just to add my experience, my water pump went out *shortly* after hitting 60k... Similar symptoms. Agree with doing thermostat at the same time.

MacE90 · 12-09-2016, 11:00 AM

I also am experiencing this code and oil temp never reaches operating temperature in cold weather. I replaced the water pump and thermostat and still have the same problem. Comments?! I am running an aftermarket radiator (CFS) and will be putting the stock unit back, along with a new temperature sensor. Wtf?!

JETmn · 12-09-2016, 11:49 AM

If you aren't reaching temp the thermostat is the main control for that. I would double check connections on that. Possibly the thermostat for oil (if you have remote oil cooler)? I wouldn't think that could hold temps down low enough on its own, but maybe in the cold it could.

MacE90 · 12-09-2016, 12:37 PM

Quote:

Originally Posted by JETmn

If you aren't reaching temp the thermostat is the main control for that. I would double check connections on that. Possibly the thermostat for oil (if you have remote oil cooler)? I wouldn't think that could hold temps down low enough on its own, but maybe in the cold it could.

My money is on the coolant temperature sensor because I found a shadow code for it along with the 348a code (go n55 mhd!!). I'll report back if that fixed it! Sorry for the thread highjack, OP!!

MacE90 · 12-20-2016, 09:10 PM

Came across a thread on n54tech about a bt jb4 connect kit being powered by the 12v 50amp fuse (same power source as the jb4) and causing CANbus issues. My bt jb4 connect kit is also powered by the 50 amp fuse. I switched it to a different hot wire in the wire loom and no more 348a code and my cooling system is back to normal function.

11-28-2016, 04:21 PM	#1
wtobiason Private First Class 15 Rep 160 Posts Drives: 2018 BMW M4 Join Date: Jun 2014 Location: San Diego CA iTrader: (1)	11 335i N55 throwing 348A code. Thermostat? I was driving to work today and lost all power. I could maintain speed but no acceleration. The cooling fan was on high too. I contacted Burger tuning with the code my JB4 gave me and they said it was "348A is a thermostat jammed open code" What could be causing this? Is the thermostat dead or is there somehting else that might be causing this? Thanks all for your input.
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11-28-2016, 04:22 PM	#2
Peen Private First Class 41 Rep 156 Posts Drives: 2011 BMW 335i Sedan Join Date: Dec 2015 Location: San Diego, CA iTrader: (0)	Happened to me when water pump went out. Check for coolant under car? Also check for coolant in reservoir. __________________ 2011 335i / MHD E85 BEF / JB4 ISO / xHP Stage 3 TCU / VRSF Catless DP / Phoenix CP / YCW Coilovers's 6K-18K / M3 Control Arms / Enkei Raijin 18' Wheels / Michellin PSS
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11-29-2016, 07:32 AM	#3
JETmn Lieutenant Colonel 245 Rep 1,595 Posts Drives: 2011 335i xDrive Msport Join Date: Apr 2013 Location: Orlando iTrader: (0) Garage List 2011 335Xi [0.00]	Normally replace both the t-stat and water pump at the same time since they are right next to each other and both are prone to failure. Then you should be good for another 50k+ miles. __________________ 2011 335Xi 6AT - VRSF catless DP - VRSF 7" FMIC with turbo inlet pipe - VRSF chargepipe - Pure Stage 1 turbo - JB4 - E30 - xHP Stage 3 - Strongflex tension bushings - Whiteline RSFB - UUC rear swaybar
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11-29-2016, 09:58 AM	#4
Euroboost91 Private First Class 57 Rep 170 Posts Drives: 2011 BMW 335i Join Date: Apr 2011 Location: Lake Worth, FL iTrader: (1)	My car had the same issue and it turns out the waterpump failed, most likely the same in your case. __________________ 2011 E90 335i LCI 6MT \| Bagged \| IG: rrs_simplee90
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11-29-2016, 11:52 AM	#5
TeinBMW Lieutenant Colonel 133 Rep 1,945 Posts Drives: 2011 335xi Msport, Conv, Tech Join Date: May 2013 Location: Calgary iTrader: (2) Garage List 2011 BMW 335xi [7.00]	Change out the water pump and thermostat....you can keep driving it but the codes will keep coming up until your car fails. Advice: get them replaced ASAP to avoid further engine damage. __________________ \|11 335XI N55 \| M SPORT \| VRSF CP \| BMW PE \| BMS INSTAKE \| VRSF 7" IC \| MHD STAGE 2+ \| ER CP \|
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11-29-2016, 06:52 PM	#6
wtobiason Private First Class 15 Rep 160 Posts Drives: 2018 BMW M4 Join Date: Jun 2014 Location: San Diego CA iTrader: (1)	Has anyone else had this happen and the car had very little power without the CEL coming on?
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12-01-2016, 08:38 AM	#8
wtobiason Private First Class 15 Rep 160 Posts Drives: 2018 BMW M4 Join Date: Jun 2014 Location: San Diego CA iTrader: (1)	I do have the JB4 auto clear DME disabled and didn't get a code. I checked the code 1/1 and got 348A. Weird. It's going in the shop to change the thermostat. My shop recommended waiting for the water pump seeing how I have 62k miles.
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12-04-2016, 05:49 PM	#11
DunklerEngelVNV Krieger 0 Rep 6 Posts Drives: 2011 BMW 335i Join Date: Apr 2013 Location: Ventura County iTrader: (0)	Just to add my experience, my water pump went out shortly after hitting 60k... Similar symptoms. Agree with doing thermostat at the same time.
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12-09-2016, 11:00 AM	#12
MacE90 Private First Class 36 Rep 179 Posts Drives: Chevrolegs Join Date: Sep 2014 Location: MT iTrader: (1) Garage List 2011 335i xdrive [10.00]	I also am experiencing this code and oil temp never reaches operating temperature in cold weather. I replaced the water pump and thermostat and still have the same problem. Comments?! I am running an aftermarket radiator (CFS) and will be putting the stock unit back, along with a new temperature sensor. Wtf?!
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12-09-2016, 11:49 AM	#13
JETmn Lieutenant Colonel 245 Rep 1,595 Posts Drives: 2011 335i xDrive Msport Join Date: Apr 2013 Location: Orlando iTrader: (0) Garage List 2011 335Xi [0.00]	If you aren't reaching temp the thermostat is the main control for that. I would double check connections on that. Possibly the thermostat for oil (if you have remote oil cooler)? I wouldn't think that could hold temps down low enough on its own, but maybe in the cold it could. __________________ 2011 335Xi 6AT - VRSF catless DP - VRSF 7" FMIC with turbo inlet pipe - VRSF chargepipe - Pure Stage 1 turbo - JB4 - E30 - xHP Stage 3 - Strongflex tension bushings - Whiteline RSFB - UUC rear swaybar
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12-20-2016, 09:10 PM	#15
MacE90 Private First Class 36 Rep 179 Posts Drives: Chevrolegs Join Date: Sep 2014 Location: MT iTrader: (1) Garage List 2011 335i xdrive [10.00]	Came across a thread on n54tech about a bt jb4 connect kit being powered by the 12v 50amp fuse (same power source as the jb4) and causing CANbus issues. My bt jb4 connect kit is also powered by the 50 amp fuse. I switched it to a different hot wire in the wire loom and no more 348a code and my cooling system is back to normal function.
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