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P0420 and P0135 Diagnostic Issues on 2002 Chevrolet Prizm - O2 Sensor Replacement Failed?

Model: 02 chevy prizm Fault Code: P0135 Posted: 2008-01-18 23:24

I recently replaced both the oxygen (O2) sensors and the catalytic converter on my 2002 Chevrolet Prizm. After installing the new components, I cleared the fault codes by disconnecting the battery for a few minutes. The Check Engine Light (CEL) initially turned off, and I let the vehicle run for some time before shutting it down. However, approximately one hour later, the CEL reappeared. Prior to this repair, the only issue was P0420. Now, both P0420 and P0135 are present. I suspect that either the O2 sensor installation was incorrect (wiring or positioning), there may be a circuit fault, or the catalytic converter is not functioning properly—especially since I used a budget-priced converter. I'm now concerned about whether the replacement parts were compatible with my vehicle's system.

Related fault codes
P0135P0420
Comments (7)
Anonymous 2008-01-19 08:38

The issue might be due to incorrect O2 sensor installation—either wiring error or a circuit fault. If a low-quality catalytic converter was installed, it could trigger the P0420 code as well.

Anonymous 2008-01-19 11:44

Could a blown fuse related to the oxygen sensor circuit be causing this problem? Worth checking the wiring and fuses for the O2 sensor system.

Anonymous 2008-01-22 10:19

Agreed—this sounds like a wiring or installation issue rather than a faulty sensor.

Anonymous 2008-01-22 22:37

I replaced one of the new O2 sensors (before the catalytic converter) and reset the ECU yesterday. My wife drove about 50 miles, then dropped it off at work because she said the engine was bogging down severely in the morning. On my way home, I noticed it—felt like a 'spitball' stuck in a straw. Only when I first accelerated did it seem to struggle, and it felt like it would stall. After warming up, it improved slightly. There's clearly something wrong. I'm hoping the CEL stays off. I’m considering throttle position or MAF sensor issues—though I’m not sure. I already failed inspection two weeks ago due to a reset; I’ll wait another day before taking it back for re-inspection. Any suggestions on how to fix the bogging down would be greatly appreciated.

Anonymous 2008-01-23 08:21

Make sure the catalytic converter or exhaust system isn't restricted—physical blockage can cause both P0420 and P0135 codes, especially if the converter is not properly installed or is defective.

Anonymous 2008-01-23 17:44

The CEL came back on today. I’m going to have to accept that it’s a persistent issue and take it in to Chevrolet for professional diagnosis—this is getting expensive, but I’ll just have to eat the cost and let their computer diagnose it.

Anonymous 2008-01-24 16:13