What did you do to your NBS GMT800 Tahoe/Yukon Today?

strutaeng · May 3, 2026

mikez71 said:
Exactly what I was thinking! They come out real easy so I'll do that tomorrow and take a comparo pic.
Be interesting to see if the sensors read differently, or if the cylinders/injectors are imbalanced more or less..
Thinking about running some cat cleaner through it.. Never know about the additives myself..

I will see what my plugs look like in a week when my new ones arrive..
Planning to go with Denso primary O2's someday, unless they're no good?... (Would save $60 over an OEM pair)

I think Densos are good. I replaced the 4 O2 sensors on that old K3500 beater. I had a lean code on bank 2 (passenger side) and I was clueless and being a parts changer back then...(turned out to be a dead "spider injector" assembly.)

And my 04 Project Suburban did have an O2 code when I bought it, so I replaced i think both sensors on that side? Also Densos. I believe it was a heater code.

My 99 has the original O2s, now at like 286k... i did have a heater code on one, but my buddy said just toone that code out and keep on trukin'.

My 06 Suburban has 284k. Bought it with 225k. I don't know if O2s are original or not on that one?

BTW, i tried to connect my laptop to HP Tunner to do a log on my 06, but was unable to. I was using and trying various phone charger USB c cables to connect to the dongle, but none connected. I have the DVi2 model. IDK where I left my original cable for that dongle?

mikez71 · May 4, 2026

Swapped primary o2's. They don't look so different as I remembered... Must have been the sunlight. (and my cataracts and memory!)
Still, bank 1 has a little oil sheen on it which bank 2 does not.

The slower to warmup B2S1 moved to B1S1 when positions were swapped. Now primary B1 and secondary B2 are slower to warmup.
(I thought there may have been some correlation when both B2 were slower, there is not) Fuel trims pretty much identical as before.
O2 sensors warmed up in 1 min 15 seconds @ 55degF ambient. Cats started working in 1 min 45 seconds..

When lifting throttle, LTFT go up like before. Bank 1 LTFT always 2-4% higher than bank 2, like before.
(exhaust manifold leak? Two broken bolts on the ends of bank 1, vs one center bolt on bank 2)
Also see the B2S2 lean spike, and knock retard starting around 3000 rpms..
Knock retard not correlating with lean spike in previous logs.. About half my logs have KR, half don't.. I don't know why.

Jimmyy · May 4, 2026

Messed around with my non working front door speakers. Turns out the connectors had some corrosion on them. On the drivers side I ended up de-pinning the connector at the speaker.

I had bought some pin tools awhile back. They are cheaply made but did the trick.
I never missed the door chime.

yukon-coRn · May 4, 2026

Swapped out the old worn out backup camera for the new one, ahhh clear picture. I'm kinda disappointed with the radio, it doesn't have AM band and the interface is fiddly. I can mirror my phone on the radio screen so that's kinda ok.

Are the stock antennas trash ...? I noticed radio station reception being pretty weak even when the old radio was installed.

LsHart · May 4, 2026

I really think at some point imma just get a HPtuner program and just try and tear some stuff up! Paid for my startup program(as in paid someone to come and get my truck started and has got me this far. I really need to just get in on my own tuning. Sorry for the burst of thought.

blondie70 · May 4, 2026

My stock ant wouldn't work. I installed a vetical one in the normal place they would go. Works great....and as a bonus.....in a full parking lot, I just look for the Tahoe with an antenna.....no other ones have it...ha ha

blondie70 · May 4, 2026

mikez71 said:
Exactly what I was thinking! They come out real easy so I'll do that tomorrow and take a comparo pic.
Be interesting to see if the sensors read differently, or if the cylinders/injectors are imbalanced more or less..
Thinking about running some cat cleaner through it.. Never know about the additives myself..

I will see what my plugs look like in a week when my new ones arrive..
Planning to go with Denso primary O2's someday, unless they're no good?... (Would save $60 over an OEM pair)

I bought Densos and they wouldn't work. Had to get the OEM O2's. That was a bad screwup....$$$$$.....good luck

mikez71 · May 4, 2026

Jimmyy said:
I never missed the door chime.

You might miss NOT having the door chime!

blondie70 said:
I bought Densos and they wouldn't work. Had to get the OEM O2's. That was a bad screwup....$$$$$.....good luck

And they weren't from amazon? Maybe OEM is worth the extra $60..
How about Bosch? That's what's in my truck now...

yukon-coRn · May 4, 2026

blondie70 said:
My stock ant wouldn't work. I installed a vetical one in the normal place they would go. Works great....and as a bonus.....in a full parking lot, I just look for the Tahoe with an antenna.....no other ones have it...ha ha

I found on another forum that there's an amp at the antenna base that needs 12v.

GMT800 Radio Reception Issues with Aftermarket Radios - Solution

I shared this information on another forum, but thought I would put it here, as this is something that I had to figure out on my own recently. To make a long story short - I recently decided to put a backup camera on my 2006 Silverado 1500 WT (work truck). Not that I need it, but its the truck...

www.gmt800.com

mikez71 · May 6, 2026

Discovered a ghost in this truck, that likes to activate the seat heater! It turned on at least a half dozen times by itself.
Sometimes lowering the temp setting by itself. Sometimes turning on right after I got done turning it off!

Hitting the door and pushing extra hard or pressing lightly on the button didn't do anything out of the ordinary..
Searching online, it seems like the door module bugs out when it's humid for 15% of people. For 5% it's the heater switch or grounds or passenger door module. And the 80% left over, they just give up. (it has been raining a couple days, and I need a new window switch anyway..)

I've only had it 10 days and there's a new problem every day..

headlight switch dead
liftglass fell off hinge
rear window quit working
radiator leak (expected)
MAF bad
knock sensor bad
Torque converter slips
Suspension module lost comms
Catalytic efficiency code
heat seater turns on by itself

10 out of 10!

Jimmyy · May 6, 2026

Driving the yukon the other day and the hvac fan started blowing on high. I had to remove the fuse in order to shut it off. I replaced the blower control module/blower resistor with a cheap version from Amazon. That was the fix. Looks to have been replaced b/4.

mikez71 · May 6, 2026

GM must purposely engineer the failure modes to be annoying!

Received my BCM from Ewalts auto tuning..
Easy swap, and now I can select manual for the auto-door locks! No more auto door locks!

But, I need to figure out how to learn the airbag module to the BCM.. (He told me VATS and SRS need relearn)
So airbag light is on ATM. Hopefully will receive guidance on how to program soon..

LsHart · May 6, 2026

Updated the fogs to smoke!

LsHart · May 6, 2026

And ordered this to put on the back!

Electrickian · May 7, 2026

Finally picked up the body trim moldings from Wrench a Part and got em on today. Then worked on the 2015 grill emblem thats going on it

mikez71 · May 7, 2026

Heard the UPS man drop my RA order with knock sensors, sparkplugs and secondary O2's on the concrete!
Not much packing material in there..

Ohm'ed the knock sensors. 99.6 & 100 Kohms.. should be alright..

Genuine GM secondary O2 sensors made in Mexico.. Hoping I don't get those lean spikes anymore..
Cat test has been passing so far with my old O2's, so why did it code that ONE time?

41-962 double plat spark plugs don't have the protective cardboard tube over the tip..
I may wait to install these until I replace exhaust gaskets..
But I'm not sure I want to attempt it and get hung up trying to extract a broken bolt..

AND, continuing the tradition of a new problem EVERY single day, I pulled up on the ramps, and water started pouring out the back edge of my muffler! So that's where the exhaust leak is! A lot of water condenses in there! Been a couple days since warmed up, but it seemed like a half cup.

Scottydoggs · May 7, 2026

mikez71 said:
Heard the UPS man drop my RA order with knock sensors, sparkplugs and secondary O2's on the concrete!
Not much packing material in there..

Ohm'ed the knock sensors. 99.6 & 100 Kohms.. should be alright..

Genuine GM secondary O2 sensors made in Mexico.. Hoping I don't get those lean spikes anymore..
Cat test has been passing sofar with my old O2's, so why did it code that ONE time?

41-962 double plat spark plugs don't have the protective cardboard tube over the tip..
I may wait to install these until I replace exhaust gaskets..
But I'm not sure I want to attempt it and get hung up trying to extract a broken bolt..

AND, continuing the tradition of a new problem EVERY single day, I pulled up on the ramps, and water started pouring out the back edge of my muffler! So that's where the exhaust leak is! A lot of water condenses in there! Been a couple days since warmed up, but it seemed like a half cup easily..

they do sell these brackets to re clamp the manifold back tight, they work on all 4 out side corners

Amazon.com : exhaust manifold bolt repair kit

and drill a hole on the side of the muffler the water is pooling. they already come with a hole to drain out condensation. whats one more 1/8 inch hole?

mikez71 · May 7, 2026

Scottydoggs said:
and drill a hole on the side of the muffler the water is pooling. they already come with a hole to drain out condensation. whats one more 1/8 inch hole?

That's exactly the hole! Soot there, so maybe a leak on that seam internally.

Thanks, I have seen the brackets before.. but I hope not to have to do that..

mikez71 · May 7, 2026

Installed new GM secondary O2 sensors. What a pain to reach bank 1 connector!!!
Hate GM more after that. It's tucked away above the transmission. Never laid eyes on it.
Had the torsion bar crossmember up in my armpit, could barely reach it!
I am surprised I was able to mate the connectors with one hand barely reaching.
No way I could install the plastic retaining pin..

New vs old. New one looks most similar to the new Delphi sensors, does not appear to be Bosch, NTK or Denso..
Little white chalkiness on old bank 2 sensor 2, that isn't on bank 1 sensors, or Bank 2 primary..
Guessing the other sensors were changed out along the way, while this one was contaminated..
(Unless the smoke test I injected through the primary O2 hole did this? idk)

Pulled out a delphi in bank 2, and OEM in bank 1.

MUCH more stable signal overall. <-SPOILER, it was fresh out of the box, following logs show similar performance as my old sensors!
(still a little better, so far without the continuous low section of B2S2 in the graph below)

OLD o2's, bottom graph, some logs the dips aren't quite so large, but the signal is never too steady.

[The following logs only represent a fresh sensor, probably with manufacturing residue that prevented accurate oxygen readings.]

NEW o2's, not fair because engine warmer, BUT the log of it warming up is similar to the beginning of this log anyway.

COLD START, new O2. Notice no oscillation at all when cold. (only when revving, which stops after cats are warmed up)

LsHart · May 8, 2026

And then......

What did you do to your NBS GMT800 Tahoe/Yukon Today?

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