orlonda

I just had my knock sensors changed and my check engine light came on so i took it to autozone they said po402 code so i went to muffler shops and had my cats checked they said they were fine.The gas i put in is bad gas so i went and put in 93 octane reset ecu and the lights been off for about 100 miles and now its back on. Any suggestions what it could be

hypervish

If the code comes back replace the 02 sensor behind the catalytic converter. I had the same code P0420 and after I replaced that sensor the light hasn't come back, it's been at least 20k miles.

orlonda

Is there a way i can check the o2 sensor before i change it

orlonda

Would that be the downstream sensor?I found a downstream sensor for 40 on ebay motors

hypervish

Here's the DIY for that sensor, which Lexmex made: https://www.clublexus.com/forums/rx-...sor-2-diy.html

This is the sensor you need: Denso 234-4215 Oxygen Sensor,
I don't know if you can test the sensor first, I know you can test an air/fuel sensor but not sure about this 02 sensor. You would need to know the acceptable ohms.

varithms

I second changing the O2 sensors. I was quoted 700.00 and they where going to replace them anyways. So I replaced them my self and the CEL never came back on.