Computer is not ready on the O2 and EGR

DIRTBAG

MEMBER
1998 NISSAN FRONTIER
4 CYL
4WD
MANUAL
118,000 MILES

I am trying to complete my safety and emissions inspection but have the following issues. I pass the emissions, catalytic converter and EGR tests but fail on the computer saying my computer is not ready on the O2 and EGR. When I scan with my unit I get the following, O2 sensor not completed (O2 sensor heated shows completed) & EGR sensor not completed. If I drive the vehicle for 50 miles I then get a Code PO420 which is catalyst system below system threshold. But the O2 and EGR never go to reset.

I can monitor the vehicle conditions and see both the O2 sensors readouts. I have tried resetting the computer by disconnecting the battery with no improvement. And have driven the vehicle through various environments and speeds to reset the readiness monitors in the computer which do not reset. I hate to just start replacing parts without an idea for what is wrong. Especially when I can see both sensors working and have passed the emmisions and catalytic converter tests. Any ideas?

Thanks, Dave

1 Reply

MERLIN2021

MECHANIC
17,250 POSTS

The vehicle exhibits rough running or other driveability incidents,
and/or

Difficulty in setting the EGR System Readiness Test (SRT) status to CMPLT.
and/or

The vehicle does not pass inspection/maintenance (I/M) emissions (smog) test for NOx

Clean the intake manifold EGR ports.
IMPORTANT: The purpose of "ACTION" (above) is to give you a quick idea of the work you will be performing. You MUST closely follow the entire SERVICE PROCEDURE as it contains information that is essential to successfully completing this repair.
.
Finish cleaning by spraying throttle body/carburetor cleaner in and through each port.
When you're finished, the area around the smaller hole should be bare metal (silver color).