OBD2 port not recognizing new catalytic convertor

SWIMJAY

MEMBER
1997 TOYOTA T100
3.4L
6 CYL
2WD
MANUAL
175,000 MILES

I had my catalytic converter replaced, because a year ago earlier replacement (OEM unit stolen) was discovered to be not the right converter (the garage installed the converter for a 2.7 liter motor). The truck passes the smog test (California), passes the visual test, but doesn't pass the functional test - obd2 port doesn't "see" the cat.
Immediately after installation of the new cat, check engine light came on.
Installer cleared code, didn't read it.
Have driven 200+ miles since, check engine light has not come on, but still fails because OBD2 port doesn't see the new converter. Emissions test is fine.

Tuesday, January 4th, 2022 AT 6:54 AM

9 Replies

ASEMASTER6371

MECHANIC
52,797 POSTS

Good morning,

This has nothing to do with the port. The system has to do an internal test to check the cat converter. It is called a drive cycle. It is a very specific way to drive the vehicle to set the monitor to green or clear.

As far as the code is concerned, I will need that if it returns. That is important.

Normal driving will never set the monitor no matter how many miles you drive. You must follow the procedure I attached.

Keep me updated with the results.

Roy

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Tuesday, January 4th, 2022 AT 7:45 AM

SWIMJAY

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8 POSTS

I forgot to mention that my T100 is a 1997 model -- would these drive patterns still work? In the driving scenario in your instructions, does the scan tool need to be connected while running the scenario, or can it be plugged in after, to verify that it worked?

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Tuesday, January 4th, 2022 AT 10:25 AM

SWIMJAY

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I don't own a scan tool and would be using the one belonging to the cat installer. I could buy one, there's a number of them on Amazon. Could you recommend one that would meet the minimum requirements?
Thank you.

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Tuesday, January 4th, 2022 AT 10:26 AM

ASEMASTER6371

MECHANIC
52,797 POSTS

No need for a scan tool to be hooked up at all.

Just follow the instructions and have someone check and see if the monitor is set.

Roy

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Tuesday, January 4th, 2022 AT 10:28 AM

SWIMJAY

MEMBER
8 POSTS

How do I determine if the catalyst monitor is an O2S type or an AF sensor type? (Is it part of the T100, perhaps of the computer, not of the scan tool?)

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Tuesday, January 4th, 2022 AT 12:29 PM

SWIMJAY

MEMBER
8 POSTS

Also, the instructions say the MIL should be off. What is MIL, and how does one make sure it's off?
Again, thank you for your help and your patience.

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Tuesday, January 4th, 2022 AT 1:06 PM

ASEMASTER6371

MECHANIC
52,797 POSTS

You have the air/fuel sensor for the upstream O2 sensor.

The MIL is the check engine light. It stands for malfunction indicator lamp.

Roy

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Tuesday, January 4th, 2022 AT 1:35 PM

SWIMJAY

MEMBER
8 POSTS

Possible duplicate, as my original response has disappeared.
Roy, thanks for everything. Did both drive cycles, a bit difficult to go so slowly on the freeway, the only road free enough to do the 16-minute oscillation cycle, but cycles seem to have worked. On two scanners, cat converter is recognized. Will have smog test on Friday, but smog test guy thinks I'll pass. (One of the scanners that looked good was his).

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Wednesday, January 5th, 2022 AT 8:53 AM

ASEMASTER6371