2004 Chevrolet Trailblazer P0455 Error: Gas Leak Repair and Loose Gas Cap Issue
I recently experienced a significant issue with my 2004 Chevrolet Trailblazer. A gas leak was detected above the fuel tank, leading to an estimated repair cost of approximately $1,400 from the dealership—this was outside the warranty period. After researching online, I found a 'Special' 10-year return policy that covered such repairs. Although the dealer initially resisted and suggested dropping the tank for inspection, I had printed out the full 7-page policy and was confident in my coverage. Fortunately, I was eligible under this policy—no charges were applied. Two weeks later, the check engine light activated with a message indicating 'LOOSE GAS CAP' (Error Code P0455). The gas cap was securely tightened, yet the code persisted. I returned to the dealership and asked whether this new error was related to the prior tank repair. They responded that it was 'doubtful.' They cleared the code and advised me to contact them if it reappeared. However, the issue has now returned. I'm seeking input from other owners: Could a previous fuel tank repair have caused or contributed to this P045 or EVAP system error? Is there any known connection between tank repairs and P0455 in 2004 Trailblazers?
It's possible that the repair could have affected the EVAP system. A quick fix would be to replace the gas cap with a new one from the dealership and clear the code. If the P0455 returns, request a 'smoke test' of the EVAP system—this will help determine whether the repair was successful or if there's a leak in the system.