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Discussion Starter · #1 ·
I’ve posted here where my truck was going into limp mode periodically on start up with warning about a brake problem. I could clear code on idash and seemed to take care of problem.

yesterday, my day started with
Scenario:
1. Def fluid was low
2. Remote started my truck this morning and it shut off
3. Air temp this morning below freezing
4. Check engine light on, Service Emission System warning on dash, 124 miles to 65 mph max speed also on dash
5. Cleared codes with Idash, check engine light went off, other warnings remain
6. Check for recent codes “P21DD”
Reading what that means I’m left wondering what caused the problem???

Dropped truck at dealer, left idash and tuner connected. Part of me wanted to know what issue is as I am running the truck w/tuner.
Dealer states they removed tuner and ran diagnostics. No problems found, and said they have a bulletin about after market plug in tuners throwing all kinds of codes that are false. Also this is at my expense not warranty, which is fine since no damage is done but trucks computer requires reboot to eliminate codes.

I’m pretty disappointed not just for cost of tuner but I really liked the performance improvement. I also was having to keep cleaning the tmap sensor. Maybe the silver lining will be my fuel mileage getting back to normal.

arrggh…
 

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Discussion Starter · #2 ·
Nobody? I know Banks is popular mod but I sure see a ton of complaints about codes and limp mode warnings, as I was getting. If Banks is the problem that means there’s a lot of tail chasing going on thinking it’s Duramax issue
 

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I'm sorry I missed this. Yes, you should have posted right away instead of heading to the dealer. It can happen from time to time. Banks customer support is second to none. When I had code problems, they swapped out my Derringer and harness. Hopefully they didn't flag your warranty.
Standby, I follow up with that code meaning.

Cleaning the TMAP sensor is a normal thing with the L5P regardless of the tuner. Now, if you're daily driving with a Derringer setting of 6 and treating the go pedal like an on off switch, obviously you'll have to clean it more often. It's a yearly thing for me at this point.
 
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Most common issue code with the Derringer was a p1091 fuel pressure sensor code and subsequent limp. Your code isnt Derringer related. As mentioned in your other thread you have an emissions system issue which is unfortunately common on many of these trucks.
 

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Discussion Starter · #5 ·
Update: maybe I’m prematurely pointing finger, warning is back today after running fine for 150 miles yesterday. Dealer appointment Monday. Let me say, I hope it’s not the Banks as I like the improvement. I haven’t ever used the 6th setting but imagine its peppy, I run between 3 and 4 depending on IF I’m pulling a trailer
 

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2006 LBZ, 2009 LML, 2022 L5P. 1993 6.5 parked in the shed.
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Looking around in TDS the other night I saw that bulletin, it's kinda vague and, IMO, a kind of escape clause for dealers to not fix problems and blame customers......it had that tone.
 
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So, upon further review of the play, after searching this forum, P21DD appears to be a DEF tank heater code. In my opinion the tuner had nothing to do with it. Of course though, you know what they say about opinions. ;-) After you cleared the code, did you shut the truck off and open your door to power down the truck?

The codes that occur while using the Derringer relate to the TMAP, or FPR. You would be the first person that I've seen that

My guess is, this is not over with, and will be coming back to bite you again. The 21 and some 22 trucks had issues with burning up their DEF heaters. There's a fix now for it from the dealer.
 
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@Kenman202

I see your update. Remove the banks tuner before going back to the dealer. It is not causing your problem, but it will avoid an argument with your dealer.

Please see my above post. Your DEF tank heater is probably on it's way out.

As others have said, the Derringer tuner is not at fault here.

Edit...

You might also want to find a new dealer, they clearly took your money, blamed the tuner, and did not fix the problem. Zero effort in proper diagnosis.
 
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2021 Silverado 2500HD LTZ L5P
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these truck sensors are very touchy when they get unexpected data. in my truck the sb spacer sent it into limp mode after running it about 2 months.

dealer at my request removed the spacer when I brought it in and reset the limp mode and it has not re-occurred.

other issue I had in regards to aftermarket was the idash causing a tcm com failure when the idash was waking up too fast. so I set the sensitivity setting to its lowest and that has recurred in the last 30k miles.

I do wish the idash had an off by default setting I could choose and wake it up when I wanted it on
 

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@Kenman202

Further info...



Good luck in your repair.

Like I said, hopefully they didn't flag your warranty from the first trip. If so, you're going to have a real fight on your hands to get it covered.

An important thing to understand here is that TSB that I referenced is a software update that can be done before the DEF heater blows up. If your DEF heater is already blown up, you're going to need a new tank, and the software update done.
 

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Discussion Starter · #11 ·
Thanks for all the helpful input. I will take the tuner off before dropping it off. I definitely will be expecting them to cover warranty given they pushed the diagnostic and flash cost onto me. If they cover it, I’ll eat the other and chalk it up to learning experience. I’ll update next week
 
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I wanted to add something.
Depending in the iDash you have, you could be gather data log.

this can be given to Banks or dealer to help pin point the issues.

Banks support of very good. I enjoy their support a lot.
 

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Thanks for all the helpful input. I will take the tuner off before dropping it off. I definitely will be expecting them to cover warranty given they pushed the diagnostic and flash cost onto me. If they cover it, I’ll eat the other and chalk it up to learning experience. I’ll update next week
Jay from Banks here. I'd like to help before you bring the truck to the dealership. We don't want the dealership pointing fingers. If the Derringer is the culprit, we should be able to isolate the issue very quickly. Please email me your contact info. [email protected]
 

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Discussion Starter · #14 ·
Jay from Banks here. I'd like to help before you bring the truck to the dealership. We don't want the dealership pointing fingers. If the Derringer is the culprit, we should be able to isolate the issue very quickly. Please email me your contact info. [email protected]
I sent you an email. Truck already dropped off at dealer as it was in 55 max speed limp mode and would have dropped to less in 75miles.
 

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Discussion Starter · #15 ·
Update: Dealer replaced DEF tank today, fully covered which was good. I did not remove the tuner, it just not plugged in but they didn’t say anything about it. I’m glad because I want to connect it after a couple days running with no issues from new def tank. Jay reached out from Banks as well which is remarkable in this day and age of poor customer service. Appreciate that!
 

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Glad to hear. Yes, banks takes their customer service very seriously.
You're right, these days that seems like a rarity, but as you see, is clearly doable.
 

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2020 L5P Z71, 2018 L5P High Country
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I removed my iDash with logger, derringer and pedal monster, when I took my 2020 in for 7500 mile service. They knew exactly what brand and when I had it on. I acted stupid, and said nothing. relationship with that dealer, where I bought two new cars that year, immediately fell apart. I did not lie to them, simply would not acknowledge what they were saying. I am sure my truck is flagged now. I took it once to a different dealer, but the quality of service was lacking there. They didn’t care about much of anything, especially doing a good job.
I bought an 11k lift, for my pole barn, and now do my own service. I love both of my trucks, and enjoy the fancy gizmos, but my next “new” truck will be a pre-govermental over-reach model.
 

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I thought the Banks stuff didn't leave any kind of tattle tale in the ECM since it isn't like a conventional tune (re programming).
 

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I thought the Banks stuff didn't leave any kind of tattle tale in the ECM since it isn't like a conventional tune (re programming).
One of the other guys on here was talking about this not that long ago. I can't remember who it was now, but they also asserted that GM can tell on the newer models if anything is plugged into the OBD port. There must be some higher level data logging capabilities with the newer ECMs.
 
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