2001 Pathfinder smog and ses light

[tee2]

Hey there,
I have a 2001 Pathfinder, with a check engine light on. The light, has has been on, for almost two years. During that 2 year period, I have replaced the hardware, that the codes are throwing, and I have even replaced the ECU. The Pathy runs beautifully. I live in CA, and have a SMOG due with my registration next month. Over here, your car would be an instant fail, if the SES light is on. I've been trying to get rid of that damn light, for a long time, and sunk far more money than I should have into that car. No one can seem to keep the light off. Not even the Nissan Dealership. I am wondering if anyone has any ideas, when it comes to passing smog, with that ses light. Thank you, for your time.

[numbnuts240]

what codes is the ecu throwing?

[tee2]

P0420 and P0105.
Already changed the MAP sensor, and the Catalytic. Codes just refuse to go away.

[MisterH]

So you replaced the CAT? What about the upstream O2 sensor?

[Rockwood]

Yes, please let us know what parts you replaced.

If you replaced the MAP sensor under the dash and the ECU, the P0105 is going to be a bad wiring connector, or a bad or loose wire.

[tee2]

Thanks, for the replies. Yup, I replaced the oxygen sensor last year, and that thing still didn't turn off. Even when I clear the codes, with my scanner, they have always come right back up, after a few restarts. Yeah, maybe there is a loose wire down there somewhere. I'm going to go check that out.

[MisterH]

Since you've obviously sunk a lot of money into the repair you may qualify for a smog test waiver under California law:

https://www.smogtips.com/register_your_car.cfm

[Rockwood]

I think you are saying you replaced the upstream oxygen sensor on the exhaust manifold.

I have had both p0420 and p0430 codes on my qx4. I fixed both by replacing the downstream sensors (after the cat). They are not very expensive on Ebay.

[r8ersazfan]

Did you get it to pass? If so, what repairs fixed it? I have a 2002 with the p0420 code.