Hello Buick LaCrosse Owners, and other GM vehicle owners

Car background:

V6, 3.0 L EngineIssues:

Has P0442 – small evap system leakComplete System Set Procedure for 2010 Buick

Turn off all accessories open hood

Set parking brake

Start engine - let idle for 2 min

Close hood - Release parking brakecontinue to operate for additional 6 minutes (5 -8 Miles)

Accelerate to 55 mph for 2 minutesNote: Do not touch accelerator pedal (Invalidates Test)Apply scan tool - All I/M systems should say YES In order for the monitor test to be invoked?

A plot of my HO2 sensor is attached (Used Android app called ODB Fusion to capture ODB-II data) Hope it is viewable

Sounds like you are on the right track. Most of these aren't driven through the exact regimen you've quoted above and most of them don't have a problem with it.

First step, clear the codes that are stored. Then Go out in weekend traffic on Saturday and drive around a bunch. Try to hit all of the conditions you noted above several times.

How'* the gas cap doing? Might be the source of the P0442 .

I am not sure about this but, but I think if P0442 sets, it won't allow the PCM to run through all of it'* diagnostic tests, like the O2 sensor.....so until P0442 is fixed, the diagnostic for the O2 sensor might not run....

Also what code was set for the O2 sensor and what was your fix?

Hi Cathedral,

I did use my Android app "ODB Fusion" to clear all codes. I have no MIL and only P0442 is present. I did check my gas cap. gasket is in good condition. I cleaned the surface thoroughly.
I screwed in the cap. Continued turning passed 2 to 3 clicks. I drive (from cold start) to work 10 miles one way Mon - Fri.

Hi Tech II,

I was hoping the emission monitor tests run independent of each other. In Texas you can have one failed monitor and still pass smog test. You may be right though, I may have to fix
the P0442 before all tests run. I had P0050 (HO2 Sensor1, Bank2). This cleared after I replaced the factory HO2 with a Bosch unit from auto zone.

The question is: Can anyone confirm that smog monitors run independent of each other, or do I need to fix P0442 issue first?

Closing this post. It seems Bonnieman and Tech II have the right answers. Thanks to all who responded.


Bonnieman in a response from 'Eric the Car Guy forum' said:

Yes, some codes prevent other I/M readiness tests from running.
I believe you misunderstand the Texas smog inspection rules. You are allowed to have 1 readiness monitor that did not run. You are not allowed to have any emissions codes.
You'll have to fix the P0442 before you can pass the inspection.
In many cases it'* the gas cap not sealing but there'* no guarantee that that is the issue. Since you're in a rather hot climate, it wouldn't be surprising if the seal has dried out somewhat..
Some people have had success by cleaning the gas cap seal and the filler tube surface, then coating the gas cap o ring with Vaseline.
Barring that, you can either get it smoke tested to pinpoint the leak or for less than $15 you can take a gamble and buy a new ACDelco gas cap.

Follow Up Info Regarding "2010 Buick Lacrosse Emissions Monitor Question"

Vehicle: 2010 Buick Lacrosse CX, 100,093 Miles on Odometer

Since the time I posted my P0442 issue to the forum, I had been trying to find the source of the evap leak being reported by my vehicle'* PCM:

Replaced purge solenoid that is mounted behind intake manifold

Drove car approx 300 miles (usual going to work drive) to see if drive would cause PCM to clear code (Nope)

Purchased a smoke machine from ebay. Performed a limited leak test on the system. Had to bypass purge solenoid because special adapter is needed to include it in the test. I was confident that replacing the original solenoid was good enough (Big mistake)

Found no leaks with smoke test

Got frustrated, so I replaced gas cap and charcoal canister purge valve. Drove car some more (300 mi) (Nope)

Research showed that this car uses natural vacuum decay method to determine if leaks are present in the system (Does not use pump)

Saw a video on youtube where the technician said "Be sure to check purge valve performance". The tech said that he found replacement purge valves that were bad out of the box (Bingo)

Checked original purge valve with Harbor Freight vacuum tool. It did not hold vacuum

Checked replacement purge valve (Purchased online). It did not hold vacuum (Bingo)

Purchased replacement purge valve from Oreillys. Checked it in the store before walking away with it (Good part!)

Found out that OBD monitors only run when a 'drive cycle' is performed or equivalent is achieved by normal driving

Had wife help me do drive cycle procedure outlined by Chilton for 2010 Buick (Twice). (Nope)

Finally gave up. Took car to a Firestone repair shop.

They smoke tested the system ($100). They said no leak. They cleared all DTCs. They said drive the car for 80 miles so all system monitors would run.

I used my ODB scan toll and found P0442 had not cleared after I brought car home. Called Firestone about my findings. They said if P0442 is still there after 80 miles, they would pass my car for state inspection.

They told me that I would have to go to a GM dealership to get my PCM re-flashed in order to clear the P0442

So I can legally drive my car for a year. I will follow up this thread after I visit a GM dealership.

Note:

Firestone contradicted themselves. First they told me I could not pass state emissions with P0442. When I returned to their shop and showed them the P0442 had never cleared, they decided I could pass emissions with "one bad engine code".

You'll need to fix the evap code.

Check evap pipe for contact with throttle body?

If no smoke was detected, then the failure is when there is a vacuum present.......A GM shop has tools/adapters to isolate sections of the system for testing.....

Normally we use nitrogen and spray with soapy water and it'll show the very small leaks that you'll not find with smoke.