ODB II System Monitors – Incomplete Smog Tests

[Fred Fender]

2010 Buick LaCrosse, 3.0 L V6

My car has P0442 (Small Evap Leak). Just recently fixed P0050 (HO2 Sensor Bad). I have replaced the correct HO2 sensor (There are 4 total HO2). My ODB II scanner shows
P0050 is now gone. I need to complete the HO2 system monitor check. It is incomplete at this time. I am trying to get my car to pass Texas State emissions. I can pass
the emissions test if I only have one bad emission code (not two). I am Following the prescribed ‘Drive Test Procedure’ taken from the Chilton’s guide for my car:

Complete 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 brake

Accelorate throttle (45-50 mph) maintain this speed for 8 minutes

continue to operate for additional 6 minutes (5 -8 Miles)

Accelerate to 55 mph for 2 minutes

Release accelorator pedal for 10 s (Allows vehicle to enter the decel fuel cut off

Note: Do not touch accelerator pedal (Invalidates Test)

Stop the vehicle with engine in drive – let vehicle idle for 2 minutes

Shift vehicle to park. Turn off engine and exit vehicle (Do not disturb for 45 minutes)

Apply scan tool – All I/M systems should say YES

I have driven over 400 miles (Trying this procedure). So far the HO2 monitor has not completed.

Q1: Do the smog monitors run independent of each other or …
Q2: Can having a P code active prevent an incomplete monitor from running to completion

I would appreciate anyone’s input regarding my situation. Thanks

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[Mike]

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’s the gas cap not sealing but there’s 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.

[Fred Fender]

Hi 6th Gear,
Thanks for setting me straight on Texas emissions rules. I will turn my attention to fixing the P0442 code at this point
I did inspect and clean the gas cap as part of my remediation efforts. I found the gas cap gasket to be in very good condition (no cracks). I did thorughly clean the gasket and the inside of the filler neck. I always tighten the cap till I hear two or three clicks.
A new gas cap is indeed cheaper than replacing potentialy bad evap valves
Thanks very much for your input.

[Author]

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