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OK, Message on dash says to service DEF system, 147 kilometers until reduced max speed 105 km/h. Code P20b9 shows up on the scanner.
I'm 275 kms from home. So finished the trip, in limp mode and took it to the dealer who informed me that my extended warranty does not cover the DEF system PERIOD! And the repair will be minimum $1000, or they could do a single stage delete for $1500 which they said wouldn't affect the rest of my extended warranty. Not being naive, I told them I would get it fixed elsewhere. Took it over to my favorite mechanic and he fixed it by installing a light bulb in place of the heater circuit, clearing the code and requesting a DEF system diagnostic on his scan tool. Total parts about $12 and an hour labour. This service got me back on the road where the truck needs to be to make any money, saved me a grand which I can put towards the delete when the ext warranty does expire. (15000 kms):grin2:
 

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That's interesting. Pretty good mek-a-nik!

I wish your signature was filled-out. What truck do you have?

My 2015, was covered. It was after the bumper to bumper ran out. Dealership still fixed under warranty. I already considered myself quite fortunate, at the time.
 

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That's interesting. Pretty good mek-a-nik!

I wish your signature was filled-out. What truck do you have?

My 2015, was covered. It was after the bumper to bumper ran out. Dealership still fixed under warranty. I already considered myself quite fortunate, at the time.
2014 Silverado LTZ Dually, used to pull a heavy tool crib all over western Canada. I figured it was still under warranty, but they called in and were told that nothing in the def system was covered.
 

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That sucks, man. It's a common problem. And, they should cover it, IMO.

Mine only took a couple hours, the first time.

Yeah, I was headed home, with a new heater and the DIC said low quality DEF detected, reduced power in blah blah blah.... I said, Oh hell, no! Went back and something had gotten screwed up during the heater replacement that took two days to track down and repair.

They gave me a loaner though. I didn't have work at the time. So, all was well with the world. I got to drive a crappy little half ton around. Made me appreciate my pickup.
 

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Temp fix

How did your mechanic install a light bulb in place of the heater circuit? I'm limited to 55mph as of today until I can get the part in on Thursday. I'm not sure if it will even last until then before it goes into limp mode? This dpf stuff is bs, I'm doing a delete asap. Go figure, I'm at 128k so warranty won't cover it
 

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Ordered 2.2 ohm resistors to put in line. They will be in on Tuesday. Spent 5 dollars on them. I am going to try and make a comprehensive video on this work around. I’m going to only leave it until I delete. I have had a new def heater in there for a year and it broke. It seems like every year I have had to put a new unit in there. What a trash part.
 

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I dropped the tank yesterday, unplugged the def heater (there are only two wires going directly into the def heater/sending unit module. Red and white wires.)

I unplugged that and clipped the wires back far enough so that I could have them hanging out when tank is back in.

(I got my 2.2 flameproof resistors in the other day off amazon)

On the clip that I took off I stripped the wires and put the resistor in line and taped it up really well.

I then plugged it back into the plug that is for the def heater.

I reassembled the def tank and put it back with the wires hanging out on the visible passenger side. I did however tuck them back into the cover for the tank.

You get 8-10 resistors in a pack. I made the whole thing quick release in the case that it ever goes out. I made a few extra resistors and threw them in the glove box just in case.

I know not everyone can afford a 2500 dollar delete kit right away and some of us are tired of putting sh** parts back inside of our vehicles that cost a lot of money.

So far everything is working. I cleared the codes and drove it around town for several hours.


Pending any issues I will post if I have them. I’m not seeing any though.

The reason this all works is because the heater has a 2-4 ohm resistance that it sends back to the computer and says “hey I’m working”. The heater is the same as a probe in your hot water heater for your home. Sometimes they bust, sometimes they get out of resistance due to temperature of the fluid in the tank. That triggers the light and trouble code to come on. So this fix is just saying “hey the resistance is right. It’s at 2.2-2.5 ohms.”

Please understand that this turns the heater off completely. So if you live in frigid temperatures, it will freeze the fluid and it will not thaw.
 

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Can you post some pics or send them to my email so I can see what you did I just got this code and I would like to try this until I can get the deletes for my truck. My email is [email protected] Also when you hooked everything back up how did you clear the service exhaust fluid system message? Did you have to go to a dealer or use a special scan tool to clear it
 

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I dropped the tank yesterday, unplugged the def heater (there are only two wires going directly into the def heater/sending unit module. Red and white wires.)

I unplugged that and clipped the wires back far enough so that I could have them hanging out when tank is back in.

(I got my 2.2 flameproof resistors in the other day off amazon)

On the clip that I took off I stripped the wires and put the resistor in line and taped it up really well.

I then plugged it back into the plug that is for the def heater.

I reassembled the def tank and put it back with the wires hanging out on the visible passenger side. I did however tuck them back into the cover for the tank.

You get 8-10 resistors in a pack. I made the whole thing quick release in the case that it ever goes out. I made a few extra resistors and threw them in the glove box just in case.

I know not everyone can afford a 2500 dollar delete kit right away and some of us are tired of putting sh** parts back inside of our vehicles that cost a lot of money.

So far everything is working. I cleared the codes and drove it around town for several hours.


Pending any issues I will post if I have them. I’m not seeing any though.

The reason this all works is because the heater has a 2-4 ohm resistance that it sends back to the computer and says “hey I’m working”. The heater is the same as a probe in your hot water heater for your home. Sometimes they bust, sometimes they get out of resistance due to temperature of the fluid in the tank. That triggers the light and trouble code to come on. So this fix is just saying “hey the resistance is right. It’s at 2.2-2.5 ohms.”

Please understand that this turns the heater off completely. So if you live in frigid temperatures, it will freeze the fluid and it will not thaw.
I know this thread is over a year old now. The reductant heater 1 in my 2011 just took a crap with code P20B9 and I tried to bypass it with a 2.2ohm 1 watt metal film resistor. When commanding the the active test on all three heaters, the test for open circuit on heater one all of a sudden kept showing fail and would not clear. Aparrently when commanding test it burned up the resistor.
My question is, what type of resistor and what wattage did you use to fix this? I refuse to keep installing heaters as well when I live in Central Florida and will never worry about frozen DEF!
Any wisdom shared with the same experience would be greatly appreciated.
 

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Power equals voltage squared divided by resistance. If the DEF heater is drawing the full 14 volt battery supply, square that value (196) and divide by the resistance (2.2 ohms), which gives you 89 watts. So use a 100 watt 2.2 ohm resistor. Your 1 watt resistor was much too low of a power rating and it burned up.
 

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Thanks for the help! I didnt think that the 1 watt would be a problem being it wouldnt draw to much current but totally over looked the power consumption. This makes total sense, already ordered new 100 watt resistor. It looks like a big sucker, has an aluminum heatsink shell encasing it. Im assuming this will work fine. I appreciation the electrical lesson.
 

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I know this thread is over a year old now. The reductant heater 1 in my 2011 just took a crap with code P20B9 and I tried to bypass it with a 2.2ohm 1 watt metal film resistor. When commanding the the active test on all three heaters, the test for open circuit on heater one all of a sudden kept showing fail and would not clear. Aparrently when commanding test it burned up the resistor.
My question is, what type of resistor and what wattage did you use to fix this? I refuse to keep installing heaters as well when I live in Central Florida and will never worry about frozen DEF!
Any wisdom shared with the same experience would be greatly appreciated.

there is no way a 1 watt resistor would be able to take the place of a heating element. You need a resistor that is rated for the same or higher wattage then the heating element runs at, with the same ohm value as the heating element.

A ball park for this would be 14 volts * the rating of the fuse for the heater would give you the max wattage of the circuit. A light bulb may work better since they are either under a vacuum, or in an inert gas which allows them to run much hotter without failure.

a 2.2 ohm resistor in a 14V circuit would dissipate about 90 watts of heat, so if 2.2 ohms works you would want a 100 watt resistor to be safe. Higher would be better, and 100 watt resistors are not exactly falling off the shelves at Walmart. You would likely also want to heatsink it.

An easy, and possibly better way to get around this value would be to use 3 6 ohm headlight resistors wired in PARALLEL. this would give you 3 50 watt resistors all sharing the load at 2.0 ohms. They come with heatsinks on them as well and mounting options.
 

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I appreciate the help guys, I had found a 2.2ohm 100watt resistor on amazon with aluminum heatsink. Will give it a try, it should work. If not a light bulb it is.
 

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Update: I installed the resistor mentioned above and secured it up above frame to where heat from aluminum heatsink could dissipate. Had shop with Autel run the three reductant heater tests and this time bye bye 55mph limit from def light. Thanks for everyones input. Hopefully it will last.
 

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Update: I installed the resistor mentioned above and secured it up above frame to where heat from aluminum heatsink could dissipate. Had shop with Autel run the three reductant heater tests and this time bye bye 55mph limit from def light. Thanks for everyones input. Hopefully it will last.
So I just got the same code, did you cut the two wires and wire them both to the resister? Or just wired it in series with one of the wires? Can you take a pic please.
 

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I dropped the tank yesterday, unplugged the def heater (there are only two wires going directly into the def heater/sending unit module. Red and white wires.)

I unplugged that and clipped the wires back far enough so that I could have them hanging out when tank is back in.

(I got my 2.2 flameproof resistors in the other day off amazon)

On the clip that I took off I stripped the wires and put the resistor in line and taped it up really well.

I then plugged it back into the plug that is for the def heater.

I reassembled the def tank and put it back with the wires hanging out on the visible passenger side. I did however tuck them back into the cover for the tank.

You get 8-10 resistors in a pack. I made the whole thing quick release in the case that it ever goes out. I made a few extra resistors and threw them in the glove box just in case.

I know not everyone can afford a 2500 dollar delete kit right away and some of us are tired of putting sh** parts back inside of our vehicles that cost a lot of money.

So far everything is working. I cleared the codes and drove it around town for several hours.


Pending any issues I will post if I have them. I’m not seeing any though.

The reason this all works is because the heater has a 2-4 ohm resistance that it sends back to the computer and says “hey I’m working”. The heater is the same as a probe in your hot water heater for your home. Sometimes they bust, sometimes they get out of resistance due to temperature of the fluid in the tank. That triggers the light and trouble code to come on. So this fix is just saying “hey the resistance is right. It’s at 2.2-2.5 ohms.”

Please understand that this turns the heater off completely. So if you live in frigid temperatures, it will freeze the fluid and it will not thaw.
 
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