My car failed emissions by .1 hydrocarbons and the pressure test. Pulled codes and only got a 91. Went under to check the O2s and the driverside one looks normal while the other is tiny! Like as thin as a pencil and maybe 2 inches long. And code 91 means the normal looking one is malfunctioning (i think). So what is the deal with the different sizes and any suggestions on passing emissions? On a side note...does anyone know what line they crimp off during the pressure test...it is something off the charcoal canister. Thanks guys.