# Check engine P20e8



## boucivicsir (Aug 17, 2021)

hello, on a roll this week... 
got a check engine, with a number of km before reduce speed.
it's P20e8 no other code at the moment
car is a 2017 TD 9 speed.
100.000kms approx (98k)
was FREEZING COLD at -30c this morning. last time I checked DEF was at around 17% ..could it have frosted? like too little in the tank and frozed, thaw etc? anyway got a 2 gallon full inside tonite, will check again tomorrow.

any input?


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## Barry Allen (Apr 18, 2018)

DEF freezes at -11ºC. The mixture of DEF is 32.5% urea and 67.5% deionized water because that has the lowest freeze point.

If you are at -30ºC the DEF is certainly frozen. There are heaters in the system so that you should get DEF flow within like 30 minutes of operating the vehicle. That's an EPA requirement for semi tractors - that they must have functional DEF systems within like an hour of starting the engine in cold temperatures.

P20E8 means low DEF pressure detected. The system is probably freaking out about the frozen DEF. If the code doesn't go away after a good time of driving, it could mean the heaters in your DEF system are not functioning properly.


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## boucivicsir (Aug 17, 2021)

Barry Allen said:


> DEF freezes at -11ºC. The mixture of DEF is 32.5% urea and 67.5% deionized water because that has the lowest freeze point.
> 
> If you are at -30ºC the DEF is certainly frozen. There are heaters in the system so that you should get DEF flow within like 30 minutes of operating the vehicle. That's an EPA requirement for semi tractors - that they must have functional DEF systems within like an hour of starting the engine in cold temperatures.
> 
> P20E8 means low DEF pressure detected. The system is probably freaking out about the frozen DEF. If the code doesn't go away after a good time of driving, it could mean the heaters in your DEF system are not functioning properly.


Def tank was pretty low so maybe it frozed over. I'll try to take the car for a 30 minutes spin... But it's very cold yet again this week.
I'll keep you guys posted.


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## boucivicsir (Aug 17, 2021)

boucivicsir said:


> Def tank was pretty low so maybe it frozed over. I'll try to take the car for a 30 minutes spin... But it's very cold yet again this week.
> I'll keep you guys posted.


light came off, all is good, took 20 minutes at least. all of a sudden, light came off.


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## Barry Allen (Apr 18, 2018)

Yep, probably frozen DEF.


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