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Discussion Starter · #1 ·
2016 Colorado Z71 4WD 2.8L Diesel.
I have a weird issue. My DEF tank always reads the level as "OK". The only way I know that it is empty is when I get a "DEF Quality" light on the dashboard. Once I fill the tank and run it for a few miles, the light goes off. The dealership is blowing sunshine up my wazzo.. This has been going on for over 30K miles and they are telling me that it might take 3 key cycles to properly recognize the proper level. BS.. It never registers anything other than 'OK", even when empty.

I figure that the computer is seeing the level as "OK", even when empty and triggering the quality light. Makes sense. If the computer thinks that there is DEF and the exhaust quality is crap, it will think I put the wrong fluid in it.

Any ideas? I'm about to shotgun the DEF pump and see if it registers the correct levels after replacement.
 

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2016 Colorado Z71 4WD 2.8L Diesel.
I have a weird issue. My DEF tank always reads the level as "OK". The only way I know that it is empty is when I get a "DEF Quality" light on the dashboard. Once I fill the tank and run it for a few miles, the light goes off. The dealership is blowing sunshine up my wazzo.. This has been going on for over 30K miles and they are telling me that it might take 3 key cycles to properly recognize the proper level. BS.. It never registers anything other than 'OK", even when empty.

I figure that the computer is seeing the level as "OK", even when empty and triggering the quality light. Makes sense. If the computer thinks that there is DEF and the exhaust quality is crap, it will think I put the wrong fluid in it.

Any ideas? I'm about to shotgun the DEF pump and see if it registers the correct levels after replacement.
When the DEF is injected it's rate of injection is directly related to the amount of NOX in the exhaust stream. If no DEF is being injected (because the tank is empty) the NOX level would be high. At that point the ECM would command the DEF injector to deliver more DEF. If the level stayed to high then it would most likely think the DEF was bad because it's not doing it's job correctly and lowering the NOX level.

If it were me I would just toss some DEF in every 5K miles or so and let it be. It's one less thing to put your vehicle into limp mode.
 

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Discussion Starter · #3 ·
You might be correct about letting it be. Its just annoying that I cannot get this to work properly. I spent a lot of $$$ on this truck specifically for the diesel. Now I'm kinda regretting it. I should not have to just deal with these issues and move on. I expect better from GM.

It also randomly throws a code and warns that I only have 175 miles until 65MPH. I drive it for about 5 minutes and the warning goes away. I took it to the dealership and they cannot find the code nor did it save it. They think I'm nuts. Between the tank not registering properly and the code; I'm at my wits end. This whole EPA emissions BS is driving me nuts. I am afraid to drive the truck any distance. What happens if that notice comes up and doesn't go away? I'm screwed and will need to stop wherever I can to get it cleared or looked at. The truck is great otherwise. I'm not sure if I will keep it. I need something stable and dependable.
 

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You might be correct about letting it be. Its just annoying that I cannot get this to work properly. I spent a lot of $$$ on this truck specifically for the diesel. Now I'm kinda regretting it. I should not have to just deal with these issues and move on. I expect better from GM.

It also randomly throws a code and warns that I only have 175 miles until 65MPH. I drive it for about 5 minutes and the warning goes away. I took it to the dealership and they cannot find the code nor did it save it. They think I'm nuts. Between the tank not registering properly and the code; I'm at my wits end. This whole EPA emissions BS is driving me nuts. I am afraid to drive the truck any distance. What happens if that notice comes up and doesn't go away? I'm screwed and will need to stop wherever I can to get it cleared or looked at. The truck is great otherwise. I'm not sure if I will keep it. I need something stable and dependable.
Well maybe the 175 mile thing is from the DEF tank level issue. Best thing you can do is take a pic of the dash if you can. At least you can get it documented. It almost sounds like a wiring harness issue. How man miles are on your truck?
 

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Discussion Starter · #5 ·
60K on the truck. Been doing this crap since the 20's. Taken it in multiple times. I keep being told that the level will register correctly after 3 key cycles. Its BS. I'm just gonna fix it myself.
These are the codes I pulled today. Once again the same issue. Once the CEL cleared the codes are gone. No history.
P20BB
P20BF

Reductant heater in the DEF tank code. But wait, Chevrolet files this under the fuel system so they don't have to cover it under the emissions systems warranty. Gotta love that ****. It's OBVIOUSLY only used for the emissions system but Chevrolet will not cover it under the emissions system warranty.

Does this heater circuit reside inside the DEF pump assembly or is it separate? If its all one unit, then I can probably fix both the level issue and the CEL issue with a DEF Pump assembly replacement.
 

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I don't know exactly but I think the in tank heater is part of the DEF pump itself. There's also a line heater external to the tank which some have had to replace.
 

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My 2018 MiniMax Colorado has never given me a "Low DEF" alarm. I have added DEF along the way, so I guess it has never gotten low enough to trigger the alarm.

I topped it off and took a trip with a car trailer from Southern California to Tampa Florida and back. From So Cal to Texas it had a Ford Pinto on it. From Dallas to Tampa it was empty, and from Naples, FL to So Cal. I had a 1970 Ford Torino with a big block in it, so not a light car. I averaged 20.7 MPG on the whole trip, and FYI, never added DEF on the trip. I got home and the next day I added 4 gallons of DEF.

I would like to see an actual DEF level indicator / gage as I've seen in other diesel vehicles myself.
 

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Discussion Starter · #8 ·
My Colorado Diesel has the DEF level indicator on the center of the dashboard under the "Info" tab. I don't know if it gives a low DEF indication. I hope it does. Mine just says that the level is "OK" all the time. I know I'm out when I get a DEF Quality error on the dashboard. It's a light on the speedometer side of the gauges.
 

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My 2019 shows DEF level percentage. I don't know what it says when it gets low. I'm sure other messages will display. My 2018 Chevy Cruze diesel DEF level display is exactly like the earlier 2016, 2017 and 2018 Colorado that others just posted. Unfortunately for me my Chevy Cruze has DEF level issues. I get a CEL and DEF level OK message disappears. One thing to look for on the earlier Colorado.
I found that the DEF pump assembly for the Cruze is the same part number as the Colorado up to the 2018 model year.
It's a obvious issue with the pump assembly regardless if it's in a Colorado or Cruze. The level sensor is part of the pump assembly. If all you are worried about is the level of the DEF fluid and no other issues related to it that might get you stranded then just top it off every oil change or so. The pump assembly is over $400, dealer is way more plus labor.
 
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