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Discussion Starter · #1 ·
I have been reading around the forums about the p20b9 code. The dealership is telling me its the glow plug module and it needs to be replaced, and of course it's not covered under the warranty. From what I have seen here most people are having their reservoir or tank heater replaced with this code? What am I missing here?


Also, has anyone ever changed a glow plug module out?

2014 Gen1 59k
 

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I have been reading around the forums about the p20b9 code. The dealership is telling me its the glow plug module and it needs to be replaced, and of course it's not covered under the warranty. From what I have seen here most people are having their reservoir or tank heater replaced with this code? What am I missing here?


Also, has anyone ever changed a glow plug module out?

2014 Gen1 59k
[FONT=&quot][h=1]OBDII diagnostics. Trouble code definition for code P20B9. Causes of error P20B9

Definition of check engine code P20B9:[/h]
[h=2]Generic (Common for all car manufacturers):[/h]
Reductant Heater "A" Control Circuit/Open
[/FONT]

[FONT=&quot][/FONT]
 

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Discussion Starter · #6 ·
So can someone help me understand this techs thought process, there is something I am missing here. I quote, "Procedure for that code tested continuity from tank heater1 to ground had more than 5 ohm. Then tested between glow plug control module and reductant heater 1 had less than 2 ohm. resistance. The next step is to replace glowplug control module and reprogram."

What does a glow plug have to due with a reductant heater? I understand ohms and resistance or maybe I am mistaken.
 

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glow plug module provides the voltage for the def heater when prompted by the pcm
Well if this is the case and the DEF tank heater is controlled and powered by the Glow Plug Module then the tech would have tested the heater circuit with an ohm meter and must have determined that the heater resistance was in spec. That would leave the Glow Plug Module as a source of the fault or a loose/open connection between the two. If they tested right from the Glow Plug Module then that only leaves the module as the problem.

It seems strange that there is not a different/more specific code for these different sources of failure, but I guess that is the way it is.
 

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Discussion Starter · #9 ·
Thank you, I live in SE Texas and freezing weather isn't really an issue here. Is there a way to bypass a **** DEF heater causing my car to limit power.
 

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Yep. Its $1500 and it's a tune and exhaust components from OZ Tuner. Not to mention they can add more power.

Sent from my ASUS_Z01BDC using Tapatalk
 

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I could be wrong, but it seems unlikely that the glow plug module is the problem. I've hot heard of that going bad in almost 4 years on the forum. I think the diagnosis is suspect. The DEF heater is covered by extended warranty. Are they willing to give you in writing that if they misdiagnose it, they will eat the cost of the module and labor? I would bet that a code (the same code) will return in short order.
 
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Discussion Starter · #12 ·
I was thinking the same thing. I've called Chevrolet regarding this dealership and the way they have treated my wife while I was at work, and them performing maintenance on my car without authorization and trying to charge me for it. They are terrible.
 

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I was thinking the same thing. I've called Chevrolet regarding this dealership and the way they have treated my wife while I was at work, and them performing maintenance on my car without authorization and trying to charge me for it. They are terrible.
Good luck getting this sorted out. Please keep us posted.
 
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Discussion Starter · #15 ·
A little update for everyone here. After fighting with Chevrolet for 3 weeks they finally got the dealership on the phone. Now the dealership is claiming p20b9 is for the glow plug module and not the tank heater. They offered a free diagnostic and if the code comes up as warranty work they will perform it, and yes you read that correctly. They are claiming p20b9 isn't the reductant tank heater. Now you see what I am working with here.
 

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A little update for everyone here. After fighting with Chevrolet for 3 weeks they finally got the dealership on the phone. Now the dealership is claiming p20b9 is for the glow plug module and not the tank heater. They offered a free diagnostic and if the code comes up as warranty work they will perform it, and yes you read that correctly. They are claiming p20b9 isn't the reductant tank heater. Now you see what I am working with here.
Wow. Working with a dealership like that is very painful. Throw logic and reasonableness out the window. Did you ask them if they've talked to GM TAC? (I'm not clear if they talked to TAC or customer service from your post).

You could also reach out to the customer service folks on this site for help too. They are a great bunch of people who can be very helpful.
 

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Discussion Starter · #17 ·
It's done. They did another free diagnostic, admitted I was right, and they were wrong and replaced the tank. They also refunded me my original diagnostic fee. Took weeks of fighting but it was worth it.
 

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It's done. They did another free diagnostic, admitted I was right, and they were wrong and replaced the tank. They also refunded me my original diagnostic fee. Took weeks of fighting but it was worth it.
It's very nice to hear this has a happy ending! Thanks for the update.
 
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