Both P1311 and P1312 are manufacture specific codes. Does anyone know what the specific fault is for these codes. Thanks

P1311 = Ion Sensing Module SEC 1 line circuit fault
P1312 = Ion Sensing Module SEC 2 line circuit fault

Sounds like either your GM/delphi :banghead: ion sensing module pooped out (it's the finned aluminum box under the plastic cover on the intake), or you are using spark plugs other than denso on your 2000+ 3.2L ONLY use the identical brand/type of spark plug that your 2000+ came with from the factory.
G/luck
Joel

some of them came with Champion plugs if so dont replace them with champions use Nippendenso if that dont work you can bet that the Ion module has taken a dump