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2014 GMC Sierra P0496 Check Engine Light Issue: Difficulty Starting After Fueling and Vibration

Model: 2014 GMC Sierra Fault Code: P0496 Posted: 2018-01-08 09:41

My 2014 GMC Sierra has a check engine light that remains on. After opening the gas cap, the truck vibrates and RPM drops significantly, but does not return to normal. This issue occurs specifically when refueling — it's difficult to start the engine after adding fuel. I've already replaced the purge valve and cleaned the EVAP canister as recommended. However, the problem persists. The diagnostic trouble code (DTC) displayed is P0496, not P0469 (which was a typo in my original post). After removing the gas cap, I notice engine vibration and RPM drop, but the engine does not shut off — this suggests an issue with the EVAP system or vacuum control. The purge valve is located under the fuel tank, not in the engine compartment as some sources suggest. I've verified that the canister was cleaned using a YouTube guide (https://www.youtube.com/watch?v=wqzZ8imD3Os), but this hasn't resolved the issue. I'm now seeking advice on how to properly diagnose and fix the P0496 code, especially regarding vacuum integrity at the purge valve and whether the vent solenoid or canister might be restricted. Any guidance on testing the purge valve (blowing through it) or diagnosing the EVAP system would be greatly appreciated.

Related fault codes
P0496
Comments (10)
Anonymous 2018-01-08 12:30

How and why was the EVAP canister cleaned? Ensure there is no engine vacuum applied to the purge valve before the canister. For more details on P0496, see official diagnostic resources.

Anonymous 2018-01-08 16:14

Did you replace the purge valve? The standard purge valve is located in the engine compartment — however, your description suggests it's under the fuel tank. Clarify this to avoid confusion.

Anonymous 2018-01-08 16:19

You mentioned P0496 in the title but listed P0469 in the body. Please confirm which code is currently being detected — it should be P0496, as that's the actual issue reported.

Anonymous 2018-01-08 16:31

The purge valve typically remains closed under normal conditions. Try blowing air through it to verify functionality and check for proper vacuum flow.

Anonymous 2018-01-08 23:34

Thanks for the clarification — I apologize, this was a typo. The correct code is indeed P0496, not P0469.

Anonymous 2018-01-08 23:36

I followed the cleaning procedure using this video: https://www.youtube.com/watch?v=wqzZ8imD3Os. It helped me understand the process — thanks for sharing!

Anonymous 2018-01-08 23:38

No, I did not replace the purge valve located in the engine compartment. The one under the fuel tank is the vent solenoid. This component is often misidentified in online guides.

Anonymous 2018-01-09 08:53

That's correct — the part under the fuel tank is the vent solenoid, not the purge valve. Many sources are outdated or incorrect about this. The vent solenoid controls airflow and must be properly functioning for P0496 to resolve.

Anonymous 2018-01-09 08:58

Difficulty adding fuel may indicate a restricted EVAP canister, though that would typically trigger a different code. Try removing the engine compartment purge valve and test if you can blow air through it — it should be closed under normal conditions.

Anonymous 2018-01-09 10:57

Thanks for the tip! I'll have my technician perform this test and provide feedback on whether the purge valve is functioning correctly or if further EVAP system diagnostics are needed.