LML service bulletin

[2004LB7]

Anyone know if there is a service bulletin, extend warranty or otherwise for the 2014 LML N2O sensors? I'm only seeing one for the earlier years but not one covering the 2014 even though they suffer from the same issue

I'm pretty sure that my uncles truck is experiencing N2O issues and monitors not setting but I haven't dug into it yet too see. Just want he is telling me is happening

 

[PureHybrid]

As far as I'm aware, all emissions system components are covered 8yrs 80k miles. That's an EPA mandate

 

[2004LB7]

Ok. So a quick scan shows the DPF monitor is not ready. Differential pressure sensor is showing 0 PSI. And about 0.5 raising the RPMs. Does this seem normal for an LML?

 

[gmc502]

-don't know the answer,I'm having readiness problem on my 16 and one of them is the NOx sensor not ready.second year in a row for me.it finally sets some time and hope tocatch it so I can pass my inspection.
no check engine light or codes.

 

[Ron Nielson]

This is a source of TSBs - https://www.tsbsearch.com/
It's not up to date, but still contains lots of info

 

[Chevy1925]

Ok. So a quick scan shows the DPF monitor is not ready. Differential pressure sensor is showing 0 PSI. And about 0.5 raising the RPMs. Does this seem normal for an LML?

That’s normal. If you saw 2-3psi, we’d have an issue.

Any codes?

 

[Chevy1925]

Also, are you trying to get it to pass smog? I think you can have 1 or 2 not ready to pass cali smog as long as no codes are set. AZ for gassers, we can have 1 not ready to pass. Diesel they don’t check monitors but we do a ton of aftertreatment repairs

 

[2004LB7]

That’s normal. If you saw 2-3psi, we’d have an issue.

Any codes?

No codes. He's put 500+ miles on it and the monitor is still not set for the DPF

Also, are you trying to get it to pass smog? I think you can have 1 or 2 not ready to pass cali smog as long as no codes are set. AZ for gassers, we can have 1 not ready to pass. Diesel they don’t check monitors but we do a ton of aftertreatment repairs

Yes. Smog check. California used to have the regular 2 but they changed it a number of years back. Now it's a little more complicated. Normally you can't have any but they added some exceptions due to many of the newer ones with complications in the emissions equipment. Looks like they say 2007 and newer can still pass with the DPF monitor not set. I'll pass that information on to him. The change for this happened in July 2023. I'm not too surprised the smog station failed him because so many still don't do diesel correctly and may not know of this change

 

[2004LB7]

Ok, little update

He took the truck back to the smog station. They are telling him he "still" has two codes (P205B & P21DD) for the DEF sensor and heater. He had a CEL earlier with these same codes so he replaced the sensor and heater with an aftermarket one and the CEL went away.

I put my V2 on it and it shows no codes. So I'm wondering if the smog station is reading the history or is my V2 not capable of reading the LML??? I checked for updates and it said I was good

I also saw this time that the reductant readyness was incomplete. Little odd considering what I scanned before

What are your experiences with aftermarket def sensors and heaters? Do they tend to do this weird stuff? Does he need to go to the dealership to get the right one or is there another one he should try?

We are going to try an Autel that another relative has to see if it says the same thing or something else

Suggestions? Before he has to take it to the dealership

 

[PureHybrid]

Are you using the v2 by itself or did you try the laptop and use scan

 

[Chevy1925]

Hook your laptop up and look.

Also, I don’t mess with aftermarket sensors or def stuff. The failure rate already sucks with factory stuff. Aftermarket seems to be worse.

Was it a whole assembly he put in the tank? Like whole pump, heater, etc or did he individually put parts in?

for the permanent codes to go away, you are going to have to actually actuate each heater so the truck sees them come on and go off. It’s not cold enough out there for the heaters to come on by themselves to clear the perminate code on its own.

 

[2004LB7]

Are you using the v2 by itself or did you try the laptop and use scan

Both

Hook your laptop up and look.

Also, I don’t mess with aftermarket sensors or def stuff. The failure rate already sucks with factory stuff. Aftermarket seems to be worse.

Was it a whole assembly he put in the tank? Like whole pump, heater, etc or did he individually put parts in?

for the permanent codes to go away, you are going to have to actually actuate each heater so the truck sees them come on and go off. It’s not cold enough out there for the heaters to come on by themselves to clear the perminate code on its own.

I used my laptop and loaded up as many pids related to emissions as I thought was relevant. Didn't see any specific to the heater other than the DEF fluid temperature. It was sitting at a consistent 26c which was pretty close to ambient. I tried the DVT tools to turn on the heater. There was two heater buttons. Had both on for 10-15 minutes and the DEF temperature stayed at 26c

From what he told me he replaced the sensor on top and the black cylinder that contains the heating element in it. Reused the pump. After the first start and drive the CEL went out on its own. He's put probably 700-800 miles on it since with no CEL.

You are right about not being cold enough to need the heaters. So is there no short interval that it turns it on right after starting the truck that the ECM checks the heater? Monitors current or resistance? They have bulb out indicators in nearly all newer vehicles. This should have been an easy one for them to design.

 

[Chevy1925]

Both

I used my laptop and loaded up as many pids related to emissions as I thought was relevant. Didn't see any specific to the heater other than the DEF fluid temperature. It was sitting at a consistent 26c which was pretty close to ambient. I tried the DVT tools to turn on the heater. There was two heater buttons. Had both on for 10-15 minutes and the DEF temperature stayed at 26c

From what he told me he replaced the sensor on top and the black cylinder that contains the heating element in it. Reused the pump. After the first start and drive the CEL went out on its own. He's put probably 700-800 miles on it since with no CEL.

You are right about not being cold enough to need the heaters. So is there no short interval that it turns it on right after starting the truck that the ECM checks the heater? Monitors current or resistance? They have bulb out indicators in nearly all newer vehicles. This should have been an easy one for them to design.

So that’s why the cel went out, it monitors resistance and when it’s not in spec, check engine light. But yeah, unless the truck turns them on due to outside temp, you have to do it. I’m not sure efi live can do it even with dvt. I usually just use the mdi2 anymore but I know our Matco Maximus will run them

 

[Chevy1925]

Also, if you can’t see perminate codes, it’s going to be real hard to know if the dvt cycled the heaters to clear the codes. I don’t think you said above you saw any?

I feel like EFI live should be able to see permanent codes because our little cheapo OBD two reader can

 

[2004LB7]

So that’s why the cel went out, it monitors resistance and when it’s not in spec, check engine light. But yeah, unless the truck turns them on due to outside temp, you have to do it. I’m not sure efi live can do it even with dvt. I usually just use the mdi2 anymore but I know our Matco Maximus will run them

EfiLive DVT has two buttons for reductant heater. Heater 1 & heater 2. I thought there was only one but??? These where the ones I cycled a few times and even left on for 10-15 minutes.

Also, if you can’t see perminate codes, it’s going to be real hard to know if the dvt cycled the heaters to clear the codes. I don’t think you said above you saw any?

I feel like EFI live should be able to see permanent codes because our little cheapo OBD two reader can

His scanner (which looked pretty good, but I don't remember what brand) and mine, the V2 / laptop both didn't show any active codes, permanent or otherwise. We will see what the Autel shows later this weekend. I know we had to use it before when he replaced the Nox sensors to do the reductant quality test so it would clear those codes. Which oddly weren't available in the EfiLive scan DVT tools

Do you know the procedure for that heater test? Do I need to have them on for any specific duration? Or reach a particular temp? Cycled a number of times?

Maybe have him drive his truck into a refrigerated warehouse to do a full test of the heater

 

[Chevy1925]

What you did was correct, I’m just not sure that efi live actually sent the command and they activated

Are all the codes cleared from the GPCM? Does it show anything in it? The GPCM is what will set the p21dd if it sees the issue with the heater

 

[2004LB7]

No code in any/all modules. But I'm not sure it was even reading them correctly.

We will see what the Autel shows later

 

[Chevy1925]

10-4, I find it very very odd they are seeing codes and you aren’t

 

[2004LB7]

Me too

 

[2004LB7]

Little update

The Autel was able to correctly cycle the heaters and clear the codes for them.

But later on a P2459 code popped up. That is interesting because the DPF monitor is what I saw the first time I scanned it. So now it's saying it's not regenerating as expected. When I last scanned it two weeks ago it said it completed one 377 miles ago. He's probably put another 250 miles on it which is still less then the 700 I'd think it would take to trigger a regen.

The soot grams was at 37 when checked with the Autel. So I guess if the additional 250 miles added enough to reach the other threshold of 42 grams.

As mentioned earlier, the pressure differential was showing 0 psi at idle and about 1/2 psi reving it up a bit.

What are the chances the sensor from my 08 working on the LML? They look identical but have different part numbers. If they can interchange then maybe we can use it to see if it fixes his issues before spending money on unknowns

Should I run a service regeneration? Seems like it should be doing it on its own and a service regen is only a bandaid if the original reason isn't found. The code will likely just return. At least he will have another two years to work on it until the next smog check time