I have a thumping sound coming from the rear. Today I noticed that the car requires premium fuel but I been using regular. Can this be the thumping cause.

 

I’m really surprised nobody offered any advice. Well if you have a similar problem. The issue is the Vapor Canister Purge Valve. 50$ part I should have been clearer I also changed the vapor canister and the vent. I figured it would be one of them but my mechanic said he thinks it was the valve.

 

thumping as a symptom is kind of ambiguous. I'm somewhat surprised that replacing the purge valve corrected your issue. What the purge valve does is it opens to allow the evap system to pull gas vapors from the tank that are trapped in the cannister back into the intake to be burned reducing emissions. Usually a failed pruge valve leads to a CEL but I've never heard of a thumping noise being a symptom. Also, running premium vs regular really shouldn't matter here - where it does matter is it helps the engine avoid knocking under load (ie misfires due to ignition via compression which can damage pistons/valves etc if it occurs repeatedly).

 

I paid 1400$ for the charcoal filter and long filter to be replaced and that wasn't the issue.