Today after about 600km of racing, cruising,city driving my check engine light came on again. Checked it with my scanner and codes po100-maf malfunction and po171-system too lean bank 1. these are the same 2 codes that showed up after I installed my the Donaldson. Could something be wrong with my mass air or do I just have a faulty o2 sensor? Anybody? I don't want to take the car to the dealer I would rather fix it myself. Thanks