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Discussion Starter · #1 ·
2010 Wagon awd, I cant get rid of the P0430 code. Had 0420 also, changed all 4 O2 sensors (bosch), both cats(one OEM GM, one who knows where it came from (was given to me with the vehicle)), the GM one is the the one throwing the code. Changed gas cap, thought it was an exhaust leak but cant find that either. Had a code for temp and changed the tstat, that went away. P0430 always comes back. any suggestions?
 

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'93 SedanDeville 60 Special
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P0430 means that the oxygen sensor downstream of the catalytic converter on bank 2 is detecting that the converter is not working as efficiently as it should be (according to specs)

When you changed O2 sensors you test with a multi meter if the O2s are getting the 12 volts for the internal heaters ?
Check fuse for heaters

Did you check wiring loom from PCM and pins at that B2S2 O2 and it's wiring pins to be clean, wires in good condition and also at the wiring loom connector at PCM ?

Is it possible the CAT you got is defective ?

Really need to use a OBD-II scanner and monitor

the long and short term fuel trims (determine that both heads (B1 and B2) show values that are balanced left/right

All 4 O2 sensors
Scanner if decent should do the PCM Onboard I/M smog tests, are they in the complete state, including the 4 O2s and the heaters of them
DO not clear the DTC until after looking at the above,
Then clear DTCs and monitor with a scanner the above when doing a cold start as that is when PCM does these tests.

I assume your O2 sensors have 4 wires

Test :
1. good ground
2. 12 volt for heater
3. The PCM sends 0.450 uVolts to the O2
4. output of O2 to the PCM


Could be a small leak, may have to use a smoker to find it. (rent. buy or make one)
 

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2011 CTS Coupe FE3, 2003 Thunderbird, Gone 2013 ATS, 02 Deville
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Discussion Starter · #4 · (Edited)
P0430 means that the oxygen sensor downstream of the catalytic converter on bank 2 is detecting that the converter is not working as efficiently as it should be (according to specs)

When you changed O2 sensors you test with a multi meter if the O2s are getting the 12 volts for the internal heaters ? i only replaced bank 1 upstream myself
Check fuse for heaters good idea

Did you check wiring loom from PCM and pins at that B2S2 O2 and it's wiring pins to be clean, wires in good condition and also at the wiring loom connector at PCM ?

Is it possible the CAT you got is defective ? doubtful - it was brand new from GM

Really need to use a OBD-II scanner and monitor i have one - what should i be monitoring?

the long and short term fuel trims (determine that both heads (B1 and B2) show values that are balanced left/right ok

All 4 O2 sensors
Scanner if decent should do the PCM Onboard I/M smog tests, are they in the complete state, including the 4 O2s and the heaters of them
DO not clear the DTC until after looking at the above,
Then clear DTCs and monitor with a scanner the above when doing a cold start as that is when PCM does these tests.

I assume your O2 sensors have 4 wires

Test :
1. good ground
2. 12 volt for heater
3. The PCM sends 0.450 uVolts to the O2
4. output of O2 to the PCM


Could be a small leak, may have to use a smoker to find it. (rent. buy or make one)
see answers above. I only replaced (myself) upstream sensor on bank 1 due to elbow surgery putting me on the sidelines for a couple months. all other work was done by a trusted shop and a reputable mechanic. not saying mistakes arent made - and i will be calling him again tomorrow. I got under it and visually checked everything when i replaced the driveshaft, did not see anything that looked out of place. replacing the driveshaft requires removing exhaust, but i was getting the code before i did that. I'll check fuses thats a good idea and easy enough to do, and bring it back.
 

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'93 SedanDeville 60 Special
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A good OBD-II scanner is more then a reader
For O2s alone since it outputs in voltage the scanner results is same as seen if using a Oscilloscope and can quickly see in looking at the data how the O2s, CATs are fuel trims are doing

The PCM uses the S1 and S2 of the same head to determine if tripping a P0420 or P0430 so the scanner can show that by the O2s output

I also can do the EPA smog I/M tests which would show up O2 or Cats issues

OP also could use like a infrared thermal tool after engine has gone closed loop and measure the temps right before the CAT and then right after it to see what it is doing or not

598853


598852
 

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Discussion Starter · #6 ·

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see answers above. I only replaced (myself) upstream sensor on bank 1 due to elbow surgery putting me on the sidelines for a couple months. all other work was done by a trusted shop and a reputable mechanic. not saying mistakes arent made - and i will be calling him again tomorrow. I got under it and visually checked everything when i replaced the driveshaft, did not see anything that looked out of place. replacing the driveshaft requires removing exhaust, but i was getting the code before i did that. I'll check fuses thats a good idea and easy enough to do, and bring it back.
The P0420 0r P0430 are tripped by the S2 (downstream ) O2s output as PCM is comparing what S1 and S2 report

Also it is always best to change the O2s as a pair as if not then one older will be slower and slew the results
Also use stock O2s and not Generic ones as O2s only work from 0 to 1 volts and the quad driver in PCM is really designed to match the OEM brand where Generic could be off a bit within that 1 volt range
 

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Discussion Starter · #8 ·
The P0420 0r P0430 are tripped by the S2 (downstream ) O2s output as PCM is comparing what S1 and S2 report

Also it is always best to change the O2s as a pair as if not then one older will be slower and slew the results
Yes, this is why I changed all 4 - I had both codes. I was given 2 cats, but the previous owner did not know that AWD cats are different than RWD. Which is why i have an ebay special sitting in my garage for bank 2. originally i was going to have mechanic change just the other 3 sensors but since i had the cats i was like might as well. turned into a huge thing and i ended up just buying a GM cat for bank 2. which looks like i probably didnt need to do
 
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