• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

CA smog legal LML

Messages
85
Likes
0
Location
Central Coast California
Thread starter #1
Hey guys, haven't been around in a bit. I sold my 6.5 and bought an LML and am having some problems with the emissions gear on it. It started with a low coolant level alarm but the tank was full, then the exhaust fluid quality alarm. I decided to take it to the dealer when it went to 55 mph restriction and then on the three hour drive home at 55 I lost butt loads of power (like 10mph going up a very small hill). I took it to the dealer and they got a bad EGT (hence the limp mode), and one or two NOX sensors that were replaced and then a run through the regen cycle and test the fluid quality. All good, for 2 days and then I got a check engine light and it turned out to be a catalytic converter alarm. The mechanic noticed that the coolant was low since he topped it off 2 days earlier and they concluded that coolant was leaking out of the EGR into the exhaust. An EGR cooler installed and 4 days later I got another service exhaust fluid alarm. Now they are saying that the sensors in the DEF tank are bad.
When the mechanic said that he tested the EGR cooler by pressurizing the coolant side and then capping it and sinking it in a bucket of water I got skeptical. There are a lot of nooks and crannies in the cooler for air to get trapped and slowly percolate out over time therefore looking like a leak. I took the EGR to work and capped on side, filled with water and put 40 PSI on the other side with a gauge and plugged it and it has been holding 42 psi for 2 days now. Is it just me or are they just replacing parts. It was $800 the first trip and $1600 2 days later. I cant wait to see what this trip is going to be to replace everything in the DEF tank. I have had the feeling since this started that it was a computer issue because I got sensors all over going bad. Sensor that don't have anything to do with each other.
Anybody have any input or experience that could lead me in the right direction? Any aftermarket equipment for CA smog legal rigs out there? Can I weld up the inside of the EGR cooler and block flow or will the computer know it?
 

BoostN

Well-Known Member
Staff member
Administrator
Messages
8,375
Likes
771
Location
Tennessee
Staff #2
How many miles are on the LML? I'm assuming it's out of warranty if you're paying that much out of pocket. I had a sensor in the DPF go bad in the first 5K I owned mine. At 30K I put a full delete on it. I still have the EGR Hardware, just disabled in the tuning.
 

WarWagon

Well it hits on 7 of 8...
Messages
8,609
Likes
3,277
Location
AZ
#4
Sensors all over going bad had bad ground written all over it. Possible wire short taking out all the sensors that share power. Do you have some upgraded ground cables and recently clean battery posts? Also check for the harness rubbing in IC plumbing. Our 2008 burned/rubbed through on the driver's side where the harness contacted the IC pipe.
 

THEFERMANATOR

FRANKENBURBAN
Staff member
Lead Moderator
Messages
9,257
Likes
2,765
Location
ZEPHYRHILLS FL
Staff #5
Sensors all over going bad had bad ground written all over it. Possible wire short taking out all the sensors that share power. Do you have some upgraded ground cables and recently clean battery posts? Also check for the harness rubbing in IC plumbing. Our 2008 burned/rubbed through on the driver's side where the harness contacted the IC pipe.
HE has an LML, COMPLETELY different truck. They share virtually nOTHING in common with the LMM other than they both use the same GMLAN for coms.
 

WarWagon

Well it hits on 7 of 8...
Messages
8,609
Likes
3,277
Location
AZ
#6
It's wiring and electrical suggested and that changes very little. Same Cheap (too small) GM wiring same GM ground issues... And the rub through on our 2008 CAC tube looks to be very rare but was included as an example of things in general to look for. Has GM finally fixed the HVAC wire burnups?

Bad grounds, bad ignition switches, bad batteries, bad battery cables, etc. all cause computers to go crazy due to low voltage. Same with unexpected shorts. That hasn't changed.

The above is merely things the OP can check for before the dealer throws more parts at it in hopes of a fix.

Going to the dealer for repairs suggests that the OP keep it 100% stock as well as CA emissions concerns. Other than now has the truck's emissions caused issues? If not I suggest 100K isn't frequent enough to try and tamper/aftermarket with it.
 
Last edited:
Top