jami1

I am not sure if this is a reminder or if there is a problem. Yesterday I filled up the gas to about half. I made sure the gas cap was tight. Later on that day I was on my way home it was raining, but not a lot. Then the CEL comes on.


The oil does have to be changed soon. I am going to take it my mechanic so he can pulled the codes probably on sunday or sat. I hope its nothing serious. its a 1998 es 300. with 190,000 miles. Oil change is due at 191000.

As far as I know mechanic checked the belts and hoses, he said the car was services before I brought it. Trans fluid was clean and oil was clean.
belts and hoses are all fine. Car seems to drive like normal.

appreciate input from all of you.

jami1

well I had my mechanic pull the codes and he got a fault in the cat converter bank 1 I think its was p0420. He cleared the codes and the check engine light went off. He said to wait and see how long it will come on again. And if it comes on again the Cat might need to be replaced.

I never had had a car where I had to replace the CAt, I have a 1998 Corolla and I have had that car for about 6 years, and didn't have to replace the cat?

I was doing some research and see that some other folks on here got the same code. and they installed a simulator O2 sensor. I would rather get it fixed. My mechanic told me that he does not put in Cat converters he said there are 2 of them in my car and its the one at the bottom that is reporting a failure. He says that its too much work for him to put a new Cat in. But he will do some checking and get back to me.

So far, i have not had any loss in power or gas mileage, everything seems to be normal.

dcapo

p0420 is your oxygen sensor on bank 1
just replace that sensor, no need for the cat, and see how that goes for u
http://www.obd-codes.com/p0420

dcapo

jami1

Thank you so much. I am not sure if the sensor are actually not working. I had my mechanic clear the codes and so far so good. if the cat was actually bad the light would have came back on immediately right?

he cleared the codes and said it rare that I would need a cat, usually I would need a sensor is what he says. after he cleared the codes he turned off the engine and and restarted it a few times to see if it came back. I drove the car so far 100 miles and everything seems fine.

jami1

Can this also mean that something is about to happen? a sensor about to go?

the2ndr

I forget what code was for the cat and 02 sensor, but i currently have 234xxx miles and in the past 15k miles I have changed the rear o2 sensor (PITA!! for me on Jack Stands) closest to the firewall and replaced the cat with a magnaflow 93506 (2.5'' universal). If your getting a code for the cat might as well order a new one(planetmagnaflow.com) and have a shop weld it on for no more than $75.

I bought a denso oem type oxygen sensor from rock auto. My car is a 97. There are actually two o2 sensors precat and one o2 sensor after the cat. Do a search on here and you'll get more info.

My cel for the cat came on and off periodically till it was replaced. Since it was replaced, no more cel's! If I can get at least 3 to 4 years with an aftermarket cat I will do that rather than buying from _______.

ivory98es3

iTrader: (1)

Becareful w/ this P0420 code. I had this happen to me and it wasn't fixed by changing the O2 sensor......P0420 means Catalyst System Effeciency below Threshold. Toyota made the ECU very tight in tolerances w/ the O2 sensor measuring how well the cat is doing.

I had my exhaust checked for leaks - none found, code still appeared...
I replaced the O2 sensor after the cat - code still appeared...
I installed a different ECU - code still appeared....
I replaced the cat/flex pipe ($750 - OUCH!) - code still appeared.....
I installed speark plug non-fowlers by the O2 sensor to pull the sensor out of the exhaust stream - no luck, code still appeared....
I then soldered in-line w/ the O2 a 3amp diode to fool the ECU - Ding, Ding, Ding!!! We have a winner - NO MORE CODE! And I get 28mpg when I drive, over 400 miles to the tank too......

jami1

wow I want to thank you both for the good information in these post. its has been a few days now, and since I have had my mechanic clear the code they have not returned. I am waiting for the CEL light again. and so far so good, (knocks on wood).

Ivory, what year is your es?

ivory98es3

iTrader: (1)

'98 - like yours....

MikeLex

If one or both pre cat O2 sensors are bad, the malfunction won't be fixed by replacing the after cat one only. The ECM compares pre and after cat waveforms generated by the sensors to check if they are oscillating at different frequencies, that is, the pre cat waveforms frequencies are supposed to be much higher than the after cat one. If they are similar, the ECM sets the P0420 code.

Fooling the ECU may not be a good idea in this case. In addition, are you sure you would pass a smog test?

ivory98es3

iTrader: (1)

Yeah, I had both Air/Fuel sensors checked and both were in spec (did an Ohm reading). As for a smog test, all Mass does is hook into your OBDII port and read the ecu, they do not put a sniffer into the tailpipe.....