Depending on the Ford engine size which is installed in your Pace Arrow RV it may or may not need catalytic converter(s). According to the Motor Engine Emission Applications Manual:
Ford 7.0 (429) heavy-duty engine does not require a CAT.
Ford 7.5 (460) medium-duty engine requires 3 CATs.
Ford 5.8 (351) medium-duty engine requires 1 CAT.
If your Pace Arrow's engine does require a catalytic converter but does not have one installed, yet never failed a smog inspection in the past it may be because of the new STAR smog check program which rolled out this year, requiring smog check technicians to be extra vigilant when performing a smog check especially when it comes to inspecting for the presence and proper fit of a catalytic converter.
