2004 Pontiac Grand Prix Catalytic Converter I/M Flag Not Ready

2004 Pontiac Grand Prix with a “2” motor will not go “Ready” with the catalytic converter test for I/M testing. I went in the service manual and did the testing for P0420 where you run the car for 1 minute in park then put in in drive while observing air/fuel mixture. The readings change from 14.7/1 to 12.3/1 then changes to 16.9 /1 as the test should do but it still says (Not Ran This Ignition) and the I/M still says “No”. I did the P0420 test 6 times, same results. I have gone over the criteria to make the test run and all readings are within specs (B+, TPS, ECT, etc).

I’m the one who had the problem with the BCM not being able to program a remote fob and also had the B1370 on every start cycle. I wonder if, since the BCM is the PMM on this car, and when the PMM isn’t seeing the correct readings at start up the rest of the modules on the Class 2 line go to a default….if that might be the reason for the non-testing of the Converter? Anyone been through this with I/M Readiness?

Thanks, in Advance.

The test you describe is checking its operation, and then the PCM would decide if it should set a code or not, this is not running the I/M. PCM will not decide to set a code or not until you have “YES”.

All accessories off. No codes stored in PCM. Engine at normal operating temp.
Accel to 55 MPH and hold for 5 minutes.
Come to an idle, in drive, at least 2 minutes.
Make sure no codes set.
Can take up to 6 times till says “YES”.
Ignition off between tries.
Certain other I/M flags must be at “YES” or this I/M will not run.

I have driven the car about 3 times on a 60 mile test drive. At the end of 30 miles every time, I sit at a stop for up to 5 mins. So far, the I/M status has never changed to “Yes”. The 2 oxygen sensor tests and the EGR have all gone to “Yes”. Next up is Converter, then Evap. The only reason I was trying the other test was to see if I could get the convertor to pass “this ignition cycle”….basically to see if it was even capable of running the I/M test. It has not even given me “passed this ignition cycle” passed yet. I’ve been with GM for quite some time and am well familiar with Driveability (that’s what I specialize in). This one is just buggy and has me semi-stumped.

Now, down to your testing that you list, “ignition off between tries???”

There must be some little thing that the PCM is seeing to not run the converter test. Obviously it is hardwired into the software so it cannot be some sort of internal glitch that prevents it from running. After coming to an idle for 2 min., shut the key off for a minute and then jump in the expressway and do the whole thing over again. That is what may take six different times.
So, did you ever get that remote programmed?

Negative on the remote programming but I want to rule out that I was sold the wrong remote (wrong part number) because, as we know, the wrong remote for a particular car will not program. So I am waiting on another remote. The one I was sold had a Delphi number so we aren’t able to cross reference.

On to the I/M testing….After a lengthy discussion with someone who is pretty good with this stuff (I consider myself pretty good with Performance too but it is always good to go over ideas with someone else, especially when guessing), we have determined that it is possible that by the BCM always setting the code B1370 upon cranking, that act allows the all other modules to work in a fail safe mode and it is possible that this mode may not allow the convertor test to run…possible. Regardless, I know it has the B1370 problem so it has to be fixed, even if it is not related with the I/M condition. So after re-running the diagnoses on the B1370, I checked the Ign1 voltage coming out of the ignition switch and it never fluctuates more than the normal slight drop in voltage from the starter engaging. So if the ignition switch is not shorted to ground or voltage, and not open during crank, then the computer must be perceiving that one of those conditions is happening during crank. That fact, along with the possibility of the it not allowing the remote to program (although I think this problem is more likely the wrong remote) gives me a probable 2 strikes against the body module, so that is what I am about to replace and reprogram.