My 4 cyl in-line 2001 Rav4 with 56,000+ miles is having problems with the OBD II reporting pending codes and Catalytic Converters are not ready since August 2004. Mass is one of those states that have gone over to using the OBD II for emissions testing and if your's happens to not work, you are in for a really rough time. I have taken it to the Dealer in Tewksbury and asked them to look at the computer, but all they wanted to do was to replace the air filter and the PCV valve and clean the throttle body for $280. I declined the work and replaced the air filter and PCV myself for $25 and took it back to the gas station for a retest and the OBD II is still not ready after 200 miles the first time and 1000+ the second time. The State EPA office referenced on the inspection report was able to setup a one time exemption after several complaint calls about the dealer, but later this year when it is due again I'm going to get screwed.
The first time the check engine light came on was 15 months after purchasing it new from the dealer, at around 22,500 miles, which the dealer flubbed around with on the first visit and after I returned for a second visit, performed the EL1011 which flashed the ECU - the repair documents do not refer to the Oxygen sensors being replaced but I think I remember noticing the tags looked clean and they told me that they replaced the 4 sensors.
The latest problem started at 53,000 when the check engine light came on while on a 400 mile trip, after the first 200 miles. When I got back from that trip, took it in for the Mass State Inspection, which it promptly failed (with the check engine light on there can be no other failures in the OBD II in order to pass). The inspection report (which has more information than the dealer was willing to print) indicates that the Cats, Evaporative system, Oxygen Sensors and Oxygen Sensor Heaters are not ready, and there were no codes stored. I have had NO battery problems, and have NOT disconnected the battery.
The State recommended that I try one of the Diagnostic centers which specialize in emission problems. I have had them look at the problem and they suggest drilling into the exhaust system and place sensors to determine if the Cats are not operating, removing the on-board sensors from the equation. It also appears that the computer is loosing the accumulated data and not allowing the codes to propagate out, continuing to call them pending codes.
Finally, 10 days ago the Check engine light came on again, and this time I have purchased a NoteBook computer, an OBDII interface with software and was able to read the codes to be P0420 and P0430 - Catalytic efficiency below threshold (both banks). Now if I could just find somebody who knew anything about what that could mean ... there is a guy on the ToyotaNation forum that has fixed the problem - only he did not specify how - only that it was the Valve Assy, Vacuum that caused it, and he has not responded in the last month.
It seems to me that this should Toyota's problem soon. Just because the local dealer is an idiot, I will have to pay to take it to the next step of isolating the problem somewhere between the Catalytic converters and the computer, which, I was told, the manufacturer has a Federally mandated responsibility to 70 or 80K.