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Have a P0420 code on a 2010 equinox 2.4l 4cyl. Just measu...


Have a P0420 code on a 2010 equinox 2.4l 4cyl. Just measured back pressure at at upstream sensor port it appears OK--at idle its around 1.25psi -1.5psi and when at 2000-2500 rpm it stays at the same reading. Is it possibly the dow...

Have a P0420 code on a 2010 equinox 2.4l 4cyl. Just measured back pressure at at upstream sensor port it appears OK--at idle its around 1.25psi -1.5psi and when at 2000-2500 rpm it stays at the same reading. Is it possibly the down stream sensor that needs checked? If so, should the pressure still be under 3psi? Mechanic's Assistant: Which particular sensor are you asking about? And have any trouble codes been triggered? Exhaust o2 sensor upstream Mechanic's Assistant: Are you fixing your Equinox yourself? What have you tried so far? Yup Mechanic's Assistant: Anything else you want the Mechanic to know before I connect you? No just code and I've check backpressure hta we have a p0420

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Automotive Expert
Hello my name is \*\*\*\*\* \*\*\*\*\* would like to assist you with your Chevy. Who do I have the pleasure of speaking with? Do you have a scanner to look at the data and graph of the oxygen sensors?

Hay Larry Im Carl. I have a scanner that's pretty old (operates on an old windows platform. I thnk it's named scan tool.net for windows.Ill send the sensor data, problem is I removed the upstream sensor to do the backpressure test and need to put it back together. I already have ordered a catalytic converter and O2 sensors but with the first reading being under 3psi i'm confused.
Automotive Expert
Hi Carl. Ok there are a couple things to also check do you have any exhaust leaks? There is a Technical service bulletin to check the coil ground wire I’ll send you the picture of that.

the sensor looks pretty dirty. As soon as the engine cools down I will shape the converter to see if its noisyinteresting about the coil ground, I would have never expected that?dont here any leaks or see any but will do a more thorough check
Automotive Expert
I know I looked up the code and there was a bulletin for that code being caused by the coil ground.

Well the converter and O2 sensors are original or might be from to when the engine was replaced by GM in 2015/16 (oil consumption issues they had with the 2.4 engine) I would assume they used the 2010 original items from the manifold out
Automotive Expert
Ok most likely it is a bad converter that’s what I see mostly with them but I do know if there are any leaks it will set that code to. Here’s a basic waveform of what the oxygen sensor data should look like when you look at your graph. The top one is normal bad bottom on would be a bad converter.

not sure my OBD tool will show me wave data but I will check the readings on the O2 sensors (Bank 1 & Bank 2 i guess) . I can get back with you later or tomorrow. The parts come in tomorrow too, How do I get back to this conversation. Is there a record that i can get back to.Where exactly is that ground wire
Automotive Expert
It’s on the engine block to the back here’s a better picture. And yes you can message me tomorrow the conversation should still be there for you to access

cantsee it very well tonight but felt around it pretty sturdy, didnt feel any frays
Automotive Expert
I just saw you asked for me but then the other tech answered I’m sorry about that. The small hole in the muffler is normal it’s to help with condensation. So most likely it’s a faulty catalytic converter. But I would still look at the sensor graphs.
Automotive Expert
Hopefully you are able to receive this still. Just let me know if you have any more questions.

Thanks
Automotive Expert
Your welcome and if you need anything else just let me know.

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