New issue with P0420 07 LS 2.2
 

Was throwing bad upsteam O2, heater, P0300 misfire so I started cheapest fix. Replaced the upsteam O2 sensor and took care of the codes and ran great. Now 2 days later I'm throwing P0132 and P0420 which I didn't have before the replacement. When I start it up, runs great for 5 minutes then sort of mimics a limp mode then throws codes and barely goes over 1000rpm. Then all of a sudden, maybe a minute or 2 later it catches and takes off like a bat out of hell. Any ideas? Bad sensor?

Both could be a result of the O2 sensor you replaced. What was the make and part number of the sensor? Was it installed correctly without any bad connections to it?

How long were you having the p0300 error, and getting what ever code it was for the upstream O2 sensor?

as per the OBD-2 website:
A code P0132 may mean that one or more of the following has happened: The oxygen sensor heater circuit is shorted out The wiring to the sensor is broken / frayed (less likely)

A code P0420 may mean that one or more of the following has happened:
Leaded fuel was used where unleaded was called for (unlikely) A damaged or failed oxygen / O2 sensor Downstream oxygen sensor (HO2S) wiring damaged or connected improperly The engine coolant temperature sensor is not working properly Damaged or leaking exhaust manifold / catalytic converter / muffler / exhaust pipe Failed or underperforming catalytic converter (likely) Retarded spark timing The oxygen sensors in front and behind the converter are reporting too similar of readings Leaking fuel injector or high fuel pressure Cylinder misfire Oil contamination

Possible Solutions:
Some suggested steps for troubleshooting and fixing a P0420 error code include: Check for exhaust leaks at the manifold, pipes, catalytic converter. Repair as required. Use a scope to diagnose the oxygen sensor operation (Tip: The oxygen sensor in front of the catalytic converter normally has a fluctuating waveform. The waveform of the sensor behind the converter should be more steady). Inspect the downstream heated oxygen sensor, replace if necessary Replace the catalytic converter

I don't have that info with me at work but I do recall, when plugging the sensor in, it seemed off but locked in place. Just didn't seem to sit well IMO. Maybe I need to pull it apart and reconnect it. Would you suggest dielectric grease?

It's a Denso 234-4668 sensor. I will go back in the history tonight to get the codes. None of them have come back since I changed the sensor except for these new codes.

Did you get Bosch sensor? They have problems. Should use NGK/NTK.

P0132 means sensor 1 (upstream) high voltage. Short to voltage.

Don't use silicone based anti-seize!!!!!!!!!!!!!!!!!! Use the copper type.

If you are luck the cat will be ok after the upstream sensor is fixed. P0420 will not clear itself, you have to disconnect the battery or use a scanner.

What does "throwing bad upstream sensor" mean? number. I see at least 6 choices.

Maybe I need a better scanner to erase the codes. I erased them but they still show up in the history. I know one was O2 sensor, another was O2 heater, evap & P0300 misfire. That's the reason I started right from the O2 sensor.

You can't erase history codes.

See my edited earlier post.

I'll hook my scanner up after I get out of work and get the numbers.

My suspicion is a wire melted.

Didn't smell any electrical when I started it up but that doesn't mean much. Can you splice these wires or no if that's the case?