How to replace evap solenoid 2010 Buick LaCrosse?

DTC P0455: Evaporative Emission (EVAP) System Large Leak

Circuit/System Description
The powertrain control module (PCM) tests the evaporative emission (EVAP) system for a large leak. The PCM monitors the fuel tank pressure (FTP) sensor signal to determine the EVAP system vacuum level. When the conditions for running are met, the PCM commands the EVAP canister purge solenoid valve OPEN and the EVAP vent solenoid valve CLOSED . This allows engine vacuum to enter the EVAP system. At a calibrated time, or vacuum level, the PCM commands the EVAP canister purge solenoid valve closed, sealing the system, and monitors the FTP sensor input in order to determine the EVAP system vacuum level. The following table illustrates the relationship between the ON and OFF states, and the OPEN or CLOSED states of the EVAP canister purge and vent solenoid valves.

The red X by the 02 sensor on your scan tool has nothing to do with.


You had the gas cap and the purge valve replaced, how about the vent valve under the back of the car. These go bad, cause large leaks. Also check the fuel fill tube,they like to rust out causing large leaks. If all that is good you may won't to it to a repair shop an have it smoke tested.

Question edited for clarity.
Question moved to model clarity.

https://www.google.com/search?q=2010+Buick+LaCrosse+3.0.+cylinder+head+bolt+Torque

could be gas cap missing or not tighten is usually the first thing that can give an evap code ---you can probably have a leak from hose cracked or not seated correctly to a damaged component -------https://www.autocodes.com/p0455_buick.html

Normally accessed from the back shelf. It slides left or right to unlatch the cover. You may have LED bulbs in the unit, in which case the whole strip have to be replaced.

https://www.google.com/search?q=2012+buick+lacrosse+third+brake+light+replacement

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Here, in the block, normally in the radiator

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Vent valve for what please.

Remove the plastic cover off top of engine . purge valve solenoid under it.

Evaporative Emission (EVAP) Canister Purge Solenoid Valve
Top rear of the engine, on the intake manifold, near the fuel injectors. If you don't know what it looks like google part to see a picture .

P0420 Catalyst efficiency below threshold Bank 1.
P0496 Evap emission high purge flow fault

follow this link as has video of the procedure which is simple but easier to send video than to type the procedure
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