Federal law requires that all 1996 and newer cars and light trucks sold in the United States be OBD II compliant. The OBD II vehicles have a common 16 pin plug to which a diagnostic tool can be attached to get a read out of any Diagnostic Trouble Codes (DTC's) and determine the run state of the OBD II Monitors. These monitors (up to eleven of them) monitor the condition of your emission systems. The good news for you is that you have a 1994.

There are continuous and non-continuous monitors. The non-continuous monitors are the troubling ones. If they haven't been run, or show that they have not been run and you go to DEQ you'll fail. If you have a problem that turns on the Check Engine Light (CEL) and you reset the DTC stored in memory to turn off the light, this also sets all the monitors to indicate "not run". This is because DEQ now uses a scan tool, and when they plug it into the OBD II, it will show the non-continuous monitors as flashing, or not run. This does not mean that there are any problems, it means that the monitor has not been run. Even though they could still use the sniffer up the pipe to perform the emissions test, they just fail your car instead. It is supposed to keep people from just resetting they CEL while their sitting in line to get their DEQ check, or some such.

For example, on July 4, I had a mis-fire in number 1 and 2 cylinders (water). This set the Check Engine Light (CEL). I put my code reader on the car, saw that I did indeed have three codes, P0300, P0301 and P0302. The 300 tells you that you have random/multiple cylinder misfires detected. the 301 and 302 tell you what cylinders (1 and 2 respectively) are the culprits. So I get everything dried out and back together, take the car out for a test drive, everything is fine. So I reset my ECM. This in turn set all the monitors to "not run". So I figure a couple of quick runs out to North Plains ought to do the trick. Yeah right!

Turns out your have to do 3 trip drive cycles to to set the monitors to "run". Well a trip drive cycle goes something like this: start engine, gear selector to drive, accelerate to 1,500 rpm, drive 5 minutes at 1,500 rpm, idle 70 seconds, with drive engaged and A/C OFF, drive 6 minutes at 1,500 rpm, idle 40 seconds, with drive engaged and A/C OFF, drive 5 minutes at 1,500.

Sorry for the long reply, but there have been a few posts about this Oregon thing.