OBD II Scan Codes P1311 & P1312

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

I have the same codes (P1311 & P1312), plus a P0300 on my 2002 rodeo with 112K miles.

I just replaced the plugs. The ones that came out were Denso K16PR-P11's.

The shop I used replaced them with Denso Iridium K16 5303.

Several parts suppliers indicate that these should be compatible. Is this the case?

I also have the following codes showing up a different times:
P0135, P0141 P0152, P1133, P1153, and P0175.

My CEL never lights up, but my code reader shows these codes. I just bought this truck about 4K miles ago and its turning into a money pit. I'm stuck in Puerto Rico without access to a mechanic that I know and trust and I have limited tools. I had one guy tell me the coils were all bad, another tell me the O2 sensors needed replacing.

It sounds to me like the cat converter is shot, but the muffler shop I found didn't seem to think so. Could a bad IMG cause a rattling exhaust sound?

My guesses are:
Dirty injectors
Bad O2 sensors
Bad Coil packs
wrong (new) plugs
Maybe a dirty EGR valve? (I used to have to clean this on my previous Rodeo every 35K)

Any suggestions on where to start?

I only use Champions in my lawn mower! Just answered a post on the exhaust rattle...could be a exhaust pipe or converter shield if it only makes noise at a certain RPM. He's got a video clip on u-tube. Check his post,see if its the same noise as yours. Thread title "Tin-y Sound".