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Discussion Starter #1
Hi I just purchased a 2001 S10 2.2L. The check engine light is on, so I put the scan tool on it, and these are the codes that came up:
P0420 (Catalyst System Low Efficiency (Bank 1)
P0440 Evaporative Emission System
P0452 Evaporative Emission System Pressure Sensor/Switch Low Input

I used the troubleshooting software that came with the scan tool, and the most likely fix is to replace the catalytic converter. That is really expensive.

Well, the troubleshooting software also listed a technical bulletin that states that the engine wire harness ground on my s10 will sometimes cause the DTC P0420 if there is a bad connection. I want to eliminate that as a potential issue, but I don't know where the engine wire harness ground is on my truck. It doesn't list my truck's ground in the bulletin. I can't find it in the repair manuals either. Can anyone tell me where to find it?

I do want to say the I have 182,550 original miles on the current catalytic converter. It may be time to replace it.
 

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Discussion Starter #3
If I replace the catalytic converter, I'll probably get it from Amazon. By the way, I live in California, so I guess I need a C.A.R.B compliant converter. Thank you for your response.

Will
 

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Check the electrical section on this forum, there are wiring diagrams and component location guides that may help you.
 

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Before you throw a few hundred into the wind check the wiring around your post cat O2 sensor for burns or abrasion. I'd spend $25-50 on a new post cat sensor before buying a CARB Compliant cat. If it doesn't fix it, it was a calculated gamble. Cats don't just go bad.
Your PCM and most sensors ground to the back of the cylinder head. It could be loose or rusty, but not likely in that part of CA.

Your evap codes are a whole different animal. Do some Google searches on "GM DTC P0440" and P0452. It sounds like either the wiring to or the Fuel Tank Pressure Sensor. If that's bad it'll cause both codes. PITA to get to, tho. You'll need to lift the drivers side of the bed to get to it.
Could also be a leaking gas cap seal. If you are that lucky.

Ever get a chance to eat at Clint's restaurant in Carmel? Last time I was there I had the chicken marinated in (IIRC) Scotch. Excellent.
My SO has family in the area.
 

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Discussion Starter #7
Thank you for your response. This vehicle was up in Washington state for quite a while. The ground may have rusted. I want to check it out. How do I test the post cat 02 sensor?

I'll do some searches regarding P0440 and P0452. I'll see what I can find. I hope it's something as simple as a gas cap seal.

I've never been to Clint's restaurant. I didn't know he had a restaurant there, until you told me. I might go there some day. It sounds like some high quality food is there.
 

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Discussion Starter #8
When I did an inspection on the evap system, I found one of the evap hoses completely shot. So I replaced it. I also replaced the gas cap for $12. I'm thinking about reseting my evap DTC codes to see if I've fixed the evap problems.
 

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Discussion Starter #9
I don't have a post cat O2 sensor. According the Haynes repair manual, I only have one O2 sensor on the exhaust manifold. I looked under the truck and I didn't see one post catalytic converter.
 

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Discussion Starter #10
So, I looked again under the truck again, and I found the post cat O2 sensor. I'm going to see if my scan tool will allow me to take live data on my post cat O2 sensor, so I can see if my catalytic converter is toast.
 

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Haynes manuals are wrong more often than they are right. Throw it out and get a FSM

The GM Factory Service manual says you have one.

 

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Discussion Starter #12
Yes! I was able to scan live data on both of my O2 sensors. It seems that my downstream O2 sensor is oscillating just like my upstream one. This means that, unfortunately, my catalytic converter is toast. I found a C.A.R.B. compliant catalytic converter on Amazon for $419. It's a direct fit, so I shouldn't have any problems installing it myself.

Hopefully, I've resolved all the issues.
 

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Specified year only. Some of the procedures may cover other years, but if it's something specific....get your year...especially for wiring. It should say what year it covers on the cover.
 
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