Typically a new Catalytic Convertor will do the trick. you don't need a factory CAT, there are many aftermarket and California legal CATs that will fit your Porsche 944. We only recommend that you ensure your 944 isn't running lean. The two things that will cause your Porsche to produce high NOx are the CAT and lean fuel condition. Lean fuel could be caused by faulty fuel injectors, defective fuel pump, and/or dirty fuel filter.
posted by SmogTips Support
