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Discussion Starter · #1 ·
I drive a 2003 RAV4.
My car failed the inspection due check engine light. I replaced both oxygen sensors and disconnected the battery. I have driven over 500 miles (drive cycle) drive on the freeway, normal driving, stop and reverse (the engine light is OFF). When I took my car for another inspection, the scanner says, "Monitor is not ready"
My questions are
1) How many miles I need to do the drive cycle before the monitor is ready
2) Does it mean the problem has been solved once the engine light is OFF
or having the check engine light OFF has nothing to do with the computer.
3) Do I need a tool to erase the old codes (p0420 and p0430)
4) Replacing both sensors are not enough, need to replace the catalyst

Your answer is greatly appreciated.

Thanks:smile
 

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Sometimes the check engine light clears if the problem is fixed. It may come back if it is not fixed. (ie resetting battery to clear trouble light but problem remains)
The trouble code is still stored in the ECM memory even if the light is gone. You must clear it with a code reader. If you live where the inspection test if there are any trouble codes in the ECM it will still be there since it is not erased.

Another thing is did you test the O2 to make sure it is the problem? Using a voltmeter verifies if it is faulty. Don't go replacing parts until you test things out. Trouble codes are not what it seems and may be other components. Codes narrow the problem to help you find the problem.

How did you find what the codes were ? Did a shop hook up your car and tested it ? You are not providing enough info.

As for the cat you are ahead of yourself. You need to test things before jumping to conclusion. There are ways to test the cat. Google on youtube.
 

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You didn't list your state but in CT, and likely most others, you must have no codes, no incomplete monitors and a working odometer. With the CE (MIL) indicator off you don't have any codes left but disconnecting the battery makes the monitors "start over." I don't know the cycles needed for them to complete but a simple reader or one at an AP store can verify they're ready.
 

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Discussion Starter · #5 ·
Paul NYC
2003 RAV4 V4 AWD 190K
Thanks all of you.
I checked the O2 sensors and they are very dirty.
I have another question due to p0420 and p0430, I know they
are related to catalytic converters.
I just want to clarify it.
There are 2 catalytic converters, one under the car (rear) and another is in the front (manifold catalytic)
not so sure what they call. Is p0420 code indicates the (manifold catalytic) and p0430 indicates the rear.
Do I need to replace both or just any one will do?

Thanks
 

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The O2 sensors are dirty after you replaced them?
 

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after doing a clear of the codes, it takes a while for all the smog checks to complete. I went thru this:

Toyota/Lexus OBD-II Drive Cycles | Car OBD Diagnostics, ECU Chip Tuning & Auto Repair Support

and the one test that didn't complete yet, finally finishes

Driving Procedure:

Connect Scan tool in order to observe data stream and monitor status.
Release pressure in the fuel tank by removing and re-installing fuel cap.
Start the engine and allow it to idle until ECT is 167E F (75E C) or more.
Raise the engine speed to 3,000 RPM for ten (10) seconds.
Idle engine with the A/C on (for additional load) for 15-50 minutes.
(If no A/C, set parking brake and chock wheels. Once immobilized, idle vehicle in drive).
 
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