P0135 And P0420 Emmisions Help

[rza36]

Hey whats going on guys,

Long time CL.com member here, just recently came across this forum and realized we have some knowledgeable people here

Here is my problem. I have 1997 ES300 with 102k miles. Had a check engine light go off, code P0135 (oxygen sensor 1 bank 1), I replaced the sensor closes to the firewall before the car. Was good for about 200 miles and light came back on again. Now I have code p0135 and p0420. I know 0420 is catlayst below threshold. But why p0135 again? Is it on because p0420 is on? I know p0420 is triggered via the rear o2 sensor (post cat). Should I replace this along with the cat? I just don't wanna spend money replacing stuff that is fine in order to track down this problem. I may just install an o2 simulator on the post cat sensor to avoid heavy repair costs. Any ideas or suggestions?

[mb12345]

Hey whats going on guys,

Long time CL.com member here, just recently came across this forum and realized we have some knowledgeable people here

Here is my problem. I have 1997 ES300 with 102k miles. Had a check engine light go off, code P0135 (oxygen sensor 1 bank 1), I replaced the sensor closes to the firewall before the car. Was good for about 200 miles and light came back on again. Now I have code p0135 and p0420. I know 0420 is catlayst below threshold. But why p0135 again? Is it on because p0420 is on? I know p0420 is triggered via the rear o2 sensor (post cat). Should I replace this along with the cat? I just don't wanna spend money replacing stuff that is fine in order to track down this problem. I may just install an o2 simulator on the post cat sensor to avoid heavy repair costs. Any ideas or suggestions?

I am in a similar situation now. I had a P0135, replaced the O2 sensor near the firewall and now I have the P0420. What did you do in your case? Did you have to replace any other O2 sensors or the cat itself?

[camlex]

First replace Cat and see what happen, I replaced both O2 sensors sametime. same part no. Bank 1 & 2.

I have 97 and it's very tricky which cat you put. my case guy bought from orailly (Brand start with W...)and no problems so far.

[mb12345]

First replace Cat and see what happen, I replaced both O2 sensors sametime. same part no. Bank 1 & 2.

I have 97 and it's very tricky which cat you put. my case guy bought from orailly (Brand start with W...)and no problems so far.

I have already replaced it twice with aftermarket converters but I still get the code. Was it the Walker brand you purchased from OReilly? Was it the universal one or direct fit? Do you remember how much you paid for it?

[camlex]

yes, Walker Universal Because previous guy try three times. thanks for remind me. total install cost was $250.

Hope that helps.

[mb12345]

yes, Walker Universal Because previous guy try three times. thanks for remind me. total install cost was $250.

Hope that helps.

Thanks. That surely helps. Do you also recall if it was the Universal Fit - Standard or the Universal Fit - Premium. The standard costs about $92 at NAPA and the premium costs about $209.