My 05 Blazer had the codes Po410 and Po455, our mechanic hooked the smoke machine up to it. It showed the vent solenoid was leaking, so he replaced the part, and cleared the service engine light. I hadn't drove it 20 miles, and the SEL came on again. So, evidently, that didn't fix it. Wondering if the mechanic didn't let the smoke machine go full circle. What else could it be? What do i need to do? HELP! (The little icon fits my mood!)