Obd Ii Catalytic Convert Monitor Never Set

[craigdetter]

A bit of background for anyone that might be interested before getting to my question.....

I have a 95 ES300 with 122K miles. I recently had a check engine light turn on. I purchased a code reader from Ebay, found it was a P0135 code turning on the MIL (Malf. Ind. Lamp which is techogeek for the Check Engine light). I purchased the Bank 1, Sensor 1 oxygen heat sensor (which is what the P0135 indicates has a problem) from the local Lexus dealer, which tested at 14 ohms between the two black leads, which is what a new one is supposed to do. According to the service manual, 11 -16 ohms at 68 deg. is within spec. The the old sensor tested totally open (infinite resistance) across the same black leads. After replacing the sensor, I erased the code, which turned off the Check Engine light, and the Oxygen Heat monitor ran to completion without turning on the MIL, problem solved. :D

Now to my question.....

Even before I replaced the oxygen sensor, the © monitor (Catalytic Converter Monitor) would constantly be running (flashing in the display of the EQUUS code reader). I presumed before replacing the sensor, that it would be set (finish the monitor cycle) once the oxygen sensor was replaced. However, that is not the case, I've driven a couple of trips since replacing the sensor and that thing just keeps running.

It may just be a matter of running more trip cycles to set the monitor, but I'm now wondering if other ES300s have the same problem or if it is normal that the monitor never stops.

Anyone had a similar experience?

[SKperformance]

you have confused me with the

Even before I replaced the oxygen sensor, the © monitor (Catalytic Converter Monitor) would constantly be running (flashing in the display of the EQUUS code reader). I presumed before replacing the sensor, that it would be set (finish the monitor cycle) once the oxygen sensor was replaced. However, that is not the case, I've driven a couple of trips since replacing the sensor and that thing just keeps running

is another code comeing up?

there are 3 sensors 2 before the cat and one after the cat.

it just might be plugged from raw fuel or damaged