Service Emmission System

[Triki_Dick]

New to me truck with 25K miles just flashed this code.  With P204B Error Code

 

Stopped by dealer and they said "Regen needed"

 

I have had the truck for two months, plenty of Def fluid and was planning on taking a trip this weekend.

 

Thanks for your advise.

[mjcmichigan]

Regen has to do with DEF.

I haven’t had an issue with mine, but have only 15k on it.


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[mjcmichigan]

Was thinking about it more. My commute is 20-40 minutes of highway driving. That’s what they want for a regen. If the previous owner did a lot of short trips and no highway... it really just might need a road trip.

Idling isn’t good enough for regen. It needs to be working a bit to regen.




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[Triki_Dick]

I drive this truck, EVERY DAY, and a hundred miles per day.  I am governed down to 55mph now!  haha!

 

There has got to be something wrong with the truck!  I made an appointment monday morning to drop truck off and get it worked on.

[mjcmichigan]

Please post when they figure it out! Thanks!

At 55mph, pulling 38 mpg?


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[Triki_Dick]

Attached is a pic of the Def fluid tank located above the spare tire.  Inside is a sensor, that went bad.  Had to replace the sensor.

[mjcmichigan]

Thanks for the update.... have a good trip with the truck...


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[newdude]

On ‎7‎/‎13‎/‎2018 at 5:54 PM, mjcmichigan said:

Regen has to do with DEF.

I haven’t had an issue with mine, but have only 15k on it.


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Regeneration's purpose is to clean the soot trap (DPF) when the exhaust pressure sensors detect a certain pressure differential pre and post DPF.  The 5th injector (or 9th on the big truck) then supplies fuel to the exhaust/DPF to heat and burn off the soot stored in the trap. 

 

DEF has nothing to do with the regen process. 

 

DEF is dosed in the exhaust at all times to eliminate NOx emissions from the exhaust.  The urea in the DEF is converted to ammonia within the exhaust, and it and the SCR breakdown the NOx into nitrogen, CO2, and water vapor.   The amount of DEF dosed is based on the readings of the 2 NOx sensors equipped in the exhaust system.  

[newdude]

On ‎7‎/‎18‎/‎2018 at 3:04 PM, Triki_Dick said:

Attached is a pic of the Def fluid tank located above the spare tire.  Inside is a sensor, that went bad.  Had to replace the sensor.

 

DTC P204B

Reductant Pressure Sensor Performance

 

Yet to see that one.  My 2016 Colorado had DEF heater #2 fail on it.  That was 8 weeks of backordered fun.  Otherwise, a swiss watch. 

[mjcmichigan]

 
Regeneration's purpose is to clean the soot trap (DPF) when the exhaust pressure sensors detect a certain pressure differential pre and post DPF.  The 5th injector (or 9th on the big truck) then supplies fuel to the exhaust/DPF to heat and burn off the soot stored in the trap. 
 
DEF has nothing to do with the regen process. 
 
DEF is dosed in the exhaust at all times to eliminate NOx emissions from the exhaust.  The urea in the DEF is converted to ammonia within the exhaust, and it and the SCR breakdown the NOx into nitrogen, CO2, and water vapor.   The amount of DEF dosed is based on the readings of the 2 NOx sensors equipped in the exhaust system.  

Thank you for the clarifications and corrections.


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