Bypass fix def heater code p20b9 until delete - Chevy and GMC Duramax Diesel Forum
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post #1 of 17 (permalink) Old 06-29-2017, 10:41 PM Thread Starter
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Talking Bypass fix def heater code p20b9 until delete

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)
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post #2 of 17 (permalink) Old 06-30-2017, 02:58 PM
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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.

Robert,

'03 Silverado, CCSB, 4WD 2500 HD,
20% injectors, ADII 165, K&N drop-in air filter,
buckstop bumper, w/ Warn powerplant winch, and PIAA fogs. Rear airbags.

'02 CCLB 2WD 2500HD
white, stock w/t w/ ZF-6 {TRADED-IN}

'15 GMC 3500 HD DRW
CCLB, 4X4 spray-in bedliner, B&W turnover, tinted tail-lights
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post #3 of 17 (permalink) Old 07-03-2017, 12:57 AM Thread Starter
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Quote:
Originally Posted by IGOU View Post
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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post #4 of 17 (permalink) Old 07-03-2017, 05:43 AM
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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.

Robert,

'03 Silverado, CCSB, 4WD 2500 HD,
20% injectors, ADII 165, K&N drop-in air filter,
buckstop bumper, w/ Warn powerplant winch, and PIAA fogs. Rear airbags.

'02 CCLB 2WD 2500HD
white, stock w/t w/ ZF-6 {TRADED-IN}

'15 GMC 3500 HD DRW
CCLB, 4X4 spray-in bedliner, B&W turnover, tinted tail-lights
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post #5 of 17 (permalink) Old 07-09-2017, 02:27 PM
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burred: Hopefully, this link works. I guess this is how mine was covered. It looks like yours should be, also.


https://gm.oemdtc.com/6957/29400-spe...-chevrolet-gmc

Robert,

'03 Silverado, CCSB, 4WD 2500 HD,
20% injectors, ADII 165, K&N drop-in air filter,
buckstop bumper, w/ Warn powerplant winch, and PIAA fogs. Rear airbags.

'02 CCLB 2WD 2500HD
white, stock w/t w/ ZF-6 {TRADED-IN}

'15 GMC 3500 HD DRW
CCLB, 4X4 spray-in bedliner, B&W turnover, tinted tail-lights
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post #6 of 17 (permalink) Old 04-10-2018, 02:13 PM
 
Join Date: Apr 2018
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Angry 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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post #7 of 17 (permalink) Old 06-17-2018, 07:34 AM
 
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I am going to attempt the bypass today. If it works I’ll let you know how it goes.
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post #8 of 17 (permalink) Old 06-17-2018, 10:37 AM
 
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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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post #9 of 17 (permalink) Old 07-04-2018, 06:00 AM
 
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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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post #10 of 17 (permalink) Old 01-16-2019, 12:27 AM
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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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