2/9 sensors not ready for emission test after driving 200 miles. Problem or just keep driving?

I had a few issues that caused my check engine light to go on. In order to check to see that it was fixed, i unplugged my battery to let the check engine light reset. Now I have driven 200 miles with at least 10-15 starts and the reader still reads 2 monitors as not ready. The oxygen sensor and catalyst are not ready. Is it normal to take this long?

Chevy Impala 2002 3.8L

You may not need to have those monitors ready in order to make the test. The requirements vary between the states. We no longer are required to do an IM test but I think at least 3 monitors needed to be set in order to proceed with the testing. There are a set of procedures you can follow in order to set the monitors but they aren’t real easy to get a hold of. Folks at the test station may have them.

Only two of nine is surprising unless that 200 miles was only one or two driving cycles.

I would drive it another week before getting concerned and pursuing other diagnostics.

Drive Cycles:

Engine fully warmed up, all accessories off.

Catalyst Drive cycle.

Start engine and bring idle speed to 2,000 RPM’s by stepping the accelerator for 6-8 minutes.

Release accelerator and allow engine to idle for 2 minutes.

Drive vehicle and at part throttle bring vehicle speed to 55 MPH for 10 minutes.

Stop vehicle and idle while in drive for 2 minutes.

O2 Sensor Drive Cycle

Start engine and allow to idle for 4 minutes.

Drive vehicle and at part throttle bring vehicle speed to 45-55 MPH for 6 minutes.


Just called an inspection station and I can get it inspected with one monitor not ready, but not 2. I’ll try the 02 sensor drive cycle soon. The engine has to be warmed up for that one?



Drove for one more day and the o2 sensor is now ready. Catalyst still isn’t yet, but I can still get it inspected. took about 250 miles of total driving with 15-20 starts. Thanks for the help.