LML service bulletin

[Chevy1925]

Your LMM nox sensor won’t work right to test. Funny enough, there is like 3 or 4 different nox 1 sensors for LML’s. We keep one of each on the shelf.

Are you sure the 9th injector is working? What’s the soot load? Does the truck blow any smoke?

You might try a forced regen to see if it will actually do it. If it won’t, let us know the reason it kicked out of doing it.

 

[2004LB7]

No smoke. Pipe is clean.

I remember a year or two ago he replaced the Nox sensors and we had to use the Autel to run the reductant quality test to clear it. Hasn't given him any trouble since. When he replaced the heater, he pull the def injector and he said it looked perfect and no deposits or crystalization. I don't remember if he looked at the 9th injector.

Soot load was 37 grams last I checked. I don't know what the ash load is. He is thinking of bringing it over so I can run a service regeneration. I told him to wait for some replies to the forum first.

He also sent be a text recently saying he just went ahead and replaced the dpf pressure sensor. If he brings it over I can check if the readings are any different then before

 

[Chevy1925]

Find out if he put a factory sensor in or not. The aftermarket is junk for aftertreatment sensors.

Basically, something is not jiving between the last regen, how much fuel it has used since then, and the readings it’s seeing. It might be regenning right away after a regen, that’s part of how that code sets.

You might need to smoke test the intake and exhaust. LML is very sensitive to intake leaks. Leaks at the turbo horn or even at the maf its self will make these things throw all kinds of weird codes yet no maf code. If the exhaust has a leak and egt’s are not reading right, it will cause this issue too.

 

[2004LB7]

Ok. Thanks

I'm pretty sure all the sensors he's purchased where aftermarket

 

[2004LB7]

Another question. On the DPF pressure sensor, does there need to be any programming for it to work correctly? My uncle said he read the pressure offset needs to be programmed in for it to work.

 

[Chevy1925]

Never had to do one but I’ll look it up

 

[Chevy1925]

Since you are at 37 grams, that might have been the issue. Needed a forced regen

 

[2004LB7]

Ok. So it looks like a forced regen is the procedure after replacing the pressure sensor.

I thought they would do an active regen at about 42 grams. Or based on miles or hours. Maybe he's hit the miles or hours and didn't let it complete fully a few times?

 

[Chevy1925]

You gotta clear the code and force the regen or it won’t do anything on its own.

You literally gotta hold the damn aftertreatments hand to make everything work again if it had an issue. It’s f-ing retarded… hence the fact you had to trigger the heaters. dodge and Chevy are the hardest to figure out as far as what kind of hand holding they need to be fixed and back working. Ford seems to have a better grasp at it.

Either way, it’s tedious and f-ing dumb.



Have I mentioned it’s dumb?

 

[2004LB7]

Crap. So, are you saying the P2459 code will prevent a service regen from starting?

If I clear it, it will reset all the monitors too. Then he's back to driving it for another few hundred+ miles to try and get the readiness monitors set. Seems like we would be starting all over

 

[Chevy1925]

Crap. So, are you saying the P2459 code will prevent a service regen from starting?

If I clear it, it will reset all the monitors too. Then he's back to driving it for another few hundred+ miles to try and get the readiness monitors set. Seems like we would be starting all over

Can’t say for sure. GM isn’t clear on it but like in that pic, it states if you are over that gram amount, you gotta clear the code and force a regen. That’s kinda their hidden way of saying it’s not going to regen without doing so.

But yeah, you are going to have to reset the monitors after