Passing Emmision's tests and codes

1997 Ford 150-V6-4.2L. I recently failed the state inspection for emmisions here in Massachusetts. I received the codes from my reader, cleared the codes and replaced the O2 sensor and cleaned some EGR parts. My question is (or was), I drove around for a week or so before I actually did the work on the truck and the CEL never came back on. Would this mean that the vehicle would have passed the state inspection for emmissions here even though the only thing I did was clear the codes with my code reader ?? I’m guessing it would have because right before I did the work, the code reader stated no codes were found. They don’t do an exhaust stick test here in Mass and I’m wondering now if all I really needed to do was clear the codes before I brought the truck in (assuming the codes were there from a “hiccup” in the emmission controls system).

Once codes are cleared you need to go through all the readiness states for the inspection to PASS.

Let me try and state this correctly. Readiness states from reset have (at times) complicated rituals that the PCM has to experience before they’re enabled. Since the trade was confounded by failing cars with codes AND upon reset not being able to have all readiness states enabled, the state(s) usually allows ONE or TWO readiness states to be incomplete with NO CEL.

The trigger for the CEL will be a failure of one of these readiness states. O2 heater circuit, EVAP:PURGE, etc. The PCM may require one “good trip” from a cold start and only light the CEL upon the second instance. That is, you can’t …fix reset…start up and drive …test. You have to fix, reset, cold start, drive …test.

My son’s 2000 had some oddball pre-cat setup that plagued owners at about 100k. I reset it and went to get it tested. NO readiness states. If the tank is too full or too empty the EVAP:PURGE won’t complete on some systems. My son’s tank was full so that wouldn’t set. So, I had to drive it around hoping that I could burn up the gas and not trip the CEL. Anyway, I managed to get all but the HEATER readiness state …and drove limited mileage for about 5 days without the CEL coming on. The heater circuit was then the wavered item.

Did that make sense? If your trips were short enough, even with a COLD START, your PCM/ECM may never have run the heater circuit readiness test …even over a week.

I’m assuming there’s no way to evaluate the “readiness states” with a simple code reader ??? So the only way I can know whether the readiness states are enabled is to have it re-tested ???

With the simple scanner, no, you won’t know. Best way is 1/2 tank and do a 25 minute duration drive. No CEL??, you can be fairly confident that all tests have been performed.

Again, they may not have to. Mass may allow one item to be un-ready.

I used to live in NuWingland …right abuv RoDialand in Attahborah. Nahtahn originally.

I found out that Mass does allow one item to be un-ready. Thanks

What motivated changing the O2 sensor and cleaning the EGR parts? If I understand correctly it sounds like you corrected a problem that might have caused caused another code and another emissions failure.

Or am I missing something?

The codes indicated the O2 sensor and EGR system. The CEL wasn’t functioning properly at the time I had it inspected, otherwise I would have corrected it first. As I understand the answers here, clearing the codes alone isn’t enough to pass the emissions part of the inspection.

The monitors on the Innova reader (Wal-Mart $97.98) will flash if they are not ready. The simple code reader came with instructions and might mention monitors. Mine does.