# P205B - DEF Temp Sensor Out of Range



## 15cruzediesel (Sep 30, 2019)

Check out the entire thread but especially #17.









P205b code


Hello, I'm a noob here. I just bought a 2012 LML and within 2 weeks owning the 58k mile truck, I got the P205b code. Made a appt with chevy dealer who said it was under warranty. That evening the dealer called and said they wouldnt cover it cause it failed their DEF test. This test was pouring...




www.dieselplace.com


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## Snipesy (Dec 7, 2015)

No just the sump unit / heater needs to be replaced.


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## LulzT1 (Aug 24, 2015)

15cruzediesel said:


> Check out the entire thread but especially #17.
> 
> 
> 
> ...


Thanks for the link, some good relative information there. I'm having a similar issue with the reported temp stuck between 104-115°F while measuring directly in the tank with IR I only see 30-40°F (even after adding a fresh 2.5gal jug at 51°F). Something isn't right...




Snipesy said:


> No just the sump unit / heater needs to be replaced.


From rockauto I can get the heater / sump ($140-190) OR what I think is a combination level/temp sensor ($75). Unless the heater includes the temp sensor? Any way to isolate the issue? Should also add the DEF level bounces around 0/33.3/66.7/100% in TorquePro, but that could also be adapter related since the DIC doesn't change ... ? 

Side note, purchased the BiScan plugin to help "see" the temp sensor values and I must say its x100 better than the SG2 I've been using the last 5 years from PIDs to labeling. Wish I purchased it sooner, oh well.


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## Snipesy (Dec 7, 2015)

LulzT1 said:


> Thanks for the link, some good relative information there. I'm having a similar issue with the reported temp stuck between 104-115°F while measuring directly in the tank with IR I only see 30-40°F (even after adding a fresh 2.5gal jug at 51°F). Something isn't right...
> 
> 
> 
> ...


The DEF level is kinda finnicky. I honesty have no idea what the DIC shows. I also don’t really know what the def level PID means.

Generally speaking unless you get a def level low message it’s fine.


anyway part 15 is the reservoir/sump unit. Commonly referred to as just the Def Heater. It is in fact a suite of sensors and the nozzles for the def pump. All in one unit. Including the level sensor.


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## BDCCruze (Jul 12, 2017)

The heater is easy to replace. I changed out mine in less than 30 minutes. The heater pump should be like 3.5 Ohms. The connector is on the right side of the ring after you pull out the foam. Mine was around 12 Ohms when it failed. And they seem to fail every 60-70k miles based on what I've seen.


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## MP81 (Jul 20, 2015)

Snipesy said:


> The DEF level is kinda finnicky. I honesty have no idea what the DIC shows. I also don’t really know what the def level PID means.
> 
> Generally speaking unless you get a def level low message it’s fine.


I wait until ours shows something other than "Level OK", and then I know I can put a 2.5 gallon jug in there without it overflowing.

Speaking of...I last filled up at the beginning of March...probably getting close.


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## 15cruzediesel (Sep 30, 2019)

MP81 said:


> I wait until ours shows something other than "Level OK", and then I know I can put a 2.5 gallon jug in there without it overflowing.
> 
> Speaking of...I last filled up at the beginning of March...probably getting close.


I thought about doing that also but I was thinking that just maybe part of the reason they fail is being run not fully in liquid or at least keeping the heater submerged.

So my theory is a portion of the def heater will be exposed to air and just maybe cause the heater to run hot since some of it isn't in def and the def is acting like a heat sink. 

I bought two one gallon jugs of def that I fill at the local truck stop every now and then. Cheap and fresh.

Call me crazy but until mine fails I am keeping it full, just in case.........


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## Snipesy (Dec 7, 2015)

15cruzediesel said:


> I thought about doing that also but I was thinking that just maybe part of the reason they fail is being run not fully in liquid or at least keeping the heater submerged.
> 
> So my theory is a portion of the def heater will be exposed to air and just maybe cause the heater to run hot since some of it isn't in def and the def is acting like a heat sink.
> 
> ...


A sound theory. The reservoir is suppose to stay full even if the outter tank is empty. But idk how wel that works in practice.


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## MP81 (Jul 20, 2015)

Snipesy said:


> A sound theory. The reservoir is suppose to stay full even if the outter tank is empty. But idk how wel that works in practice.


With vehicle movement - probably not real well, so I would definitely agree that's a good theory.


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## LulzT1 (Aug 24, 2015)

Just for confirmation, the correct part to replace is BOSCH F01C600339 which looks like a bucket with some pigtails hanging off? I assume the sensors are inside ... ?



15cruzediesel said:


> I thought about doing that also but I was thinking that just maybe part of the reason they fail is being run not fully in liquid or at least keeping the heater submerged.
> 
> So my theory is a portion of the def heater will be exposed to air and just maybe cause the heater to run hot since some of it isn't in def and the def is acting like a heat sink.
> 
> ...


This is a good observation and could prematurely burn out if not submerged. Since it takes a while to consume I typically waited until 10-15% left to ensure the whole jug fit. But if it does take all 2.5gal at 35% I will going forward.


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## LulzT1 (Aug 24, 2015)

LulzT1 said:


> Just for confirmation, the correct part to replace is *BOSCH F01C600339 (#84412930)* which looks like a bucket with some pigtails hanging off? I assume the sensors are inside ... ?


Just to follow up for completeness, I ordered the above DEF heater off Rockauto for $153 shipped. Took less than 30 mins to replace from start to finish. There are two youtube videos which show the whole process, very simple. Checked the sensor output through TorquePro and it reads 44.6°F as opposed to the 114°F I was seeing before, seems the problem is resolved. Much appreciation to you guys for the help and narrowing down the issue ! 

Also, as I mentioned in the OP in January 2018 I had P21DD at 79k miles and the dealer replaced the DEF heater with part number #23377881 under warranty. Hopefully this one lasts longer than 2 years !

Now to replace the rattling oil deflector ...


Edit:
CEL extinguished itself and my remote start works again, whoo!


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## 15cruzediesel (Sep 30, 2019)

Snipesy said:


> A sound theory. The reservoir is suppose to stay full even if the outter tank is empty. But idk how wel that works in practice.


I just recently had a def temp sensor failure.

Now that I have seen the heater my theroy doesn't hold DEF.😂

You'd be pretty much out of def before the heaters were out of solution.

What I discovered on why the heaters failed early on was because:

The faulty Emission Reduction Fluid Tank heater is caused by the tank heating elements being exposed to Diesel Exhaust Fluid (DEF) and shorting to the pump ground.

I wonder what they did to fix the problem.


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