P0157?

[sefiroxx]

P0158 reflects what you see in the scanner. It's a high voltage code and the sensor is stuck around .900mv.

Yep

Sensor 1's are fine
Sensor 2 (after cat) is high, should be in .5-.7 range. High indicates low oxygen. This can be due to o2 sensor clogged, or the cat is on its way out. Cat converts NO2 and NO to N and O2.

[DareDog]

I think i eliminated the o2 sensor being bad. Replaced all 3 of them in last year. Then swapped them from side to side and the cel code did not change. How do i test the cat? Is there a way to clean it?

 

 

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[sefiroxx]

Take it into a shop that has a tailpipe emmisions analyzer.

[CamGTP]

P0420 or P0430 are cat codes, the P0158 is strictly a circuit, wiring related code.

[sefiroxx]

Downstream Cat codes are set for signal low, signal high, low efficiency.

 

Low signal is usually a broken harness wire that the ecu sees as 0v. If it's at .01-.2 then the wire is either corroded (high resistance), or the cat has lost its ability to cover CO (CO + O2 = CO2+)

 

Efficiency failing code is set when the cat is unavailable to convert anything, and is passing the fluctuating o2 exhaust thru the cat. The downstream sensor starts looking like the upstream sensor

 

When failed high, it will show either

a) a short in the wire thus sending .5v back without any fluctuation or

B) send a consistent result above .7 - an indication of low O2. O2 is produced on N conversion activities (and consumed on the CO conversion).

 

 

[DareDog]

did some more testing with multi meter and 12 volt test light.    now since did testing with the plug,  p2a04 code comes up now.  O2 Sensor Circuit Range/Performance Bank 2 Sensor 2.

 

could it be the o2 sensor plug is bad?  

[DareDog]

tested fuel pressure, its at 61psi.  

 

going to test temperature of catalytic converter,  what should that be? 

 

so if catalytic converter is bad  is it  good to go with cheap one or not?   found online can get stainless steel one for $250.   

 

 

Edited January 5, 2021 by DareDog

[sefiroxx]

2005 1500 5.3L 160k. Gotten this code. The O2 sensors are new in last 2 years. New Acdelco parts put on. Could i have a defective part? How to tell if sensor is actually bad? Or something else? Coolant temp sensor? Truck runs normally and no decrease in fuel economy.
 
 
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If you futzed with the wire and the code changed, then yes, replace the pigtail. Once pigtail is replaced, take a test drive and see if a code returns. Then swap o2 sensors. If the code stays, then cat is gone.

[sefiroxx]

tested fuel pressure, its at 61psi.  
 
going to test temperature of catalytic converter,  what should that be? 
 
so if catalytic converter is bad  is it  good to go with cheap one or not?   found online can get stainless steel one for $250.   
 
 

Follow my recommendation on the pigtail.

As for $250 cat, you'll probably only get a few years out of it. If you want a long term solution, then get a CARB compliant version, it will have more precious metal in it.

[DareDog]

took truck to mechanic.  they put scan tool on it.  Found no issues in wiring, PCM or converter.  they say its the 02 sensor that is bad.  I just put new one on last week and still get the code.    there going to put new o2 sensor on it and see.

[DareDog]

Got truck back today. Have extender on that o2 sensor. Bought what i thought was a stainless o2 sensor extender. But Its not meant for the o2. Restricting the air flow. So that is what caused this. Tested the o2 sensor data on my scan tool. They all read .45 volts. Bank 2 volts moves up down now.

 

 

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[DareDog]

Well CEL back on. 420 and 430. Converter is bad. Looking at replacing it. What is good one? I see flowmaster for $579 on jeggs.


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