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1991 Sedan Deville 2004 Deville 2005 Escalade 2003 Deville T
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Discussion Starter #1
Hello Need some ideas thrown out here I’m getting the P0430 code. My local mechanic said that I needed a tuneup with that we also replace the valve covers with new ones. And the coils.
That’s all the problem with the check engine light not coming on for a while now it’s coming back I replaced cats
At a loss of what to do next .... O2 sensors ? Tried a cat cleaner but that only worked for a while
Coming from bank 2 is there anything I can try ? Any help you can give would be appreciated! It’s a 2009 CTS with 130k I haven’t had any real issues with car since purchase except leaking sun roof but I can live with that
 

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2011 CTS4 Performance 3.6
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13 Posts
Hello Need some ideas thrown out here I’m getting the P0430 code. My local mechanic said that I needed a tuneup with that we also replace the valve covers with new ones. And the coils.
That’s all the problem with the check engine light not coming on for a while now it’s coming back I replaced cats
At a loss of what to do next .... O2 sensors ? Tried a cat cleaner but that only worked for a while
Coming from bank 2 is there anything I can try ? Any help you can give would be appreciated! It’s a 2009 CTS with 130k I haven’t had any real issues with car since purchase except leaking sun roof but I can live with that
Get yourself a Bluetooth scanner, I recommend a obdlink. It's 50 bucks but worth it. Check fuel trims and report back what they are. Long term and short term both banks. Also, look at data from the rear O2 sensors they are labeled as oxygen sensor b1s2 and b2s2... These monitor the gases post cat. If you don't have lean or rich codes, and the the 02 sensors don't seem to be moving at all then the sensors need to be replaced.
 

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1991 Sedan Deville 2004 Deville 2005 Escalade 2003 Deville T
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Discussion Starter #3
Get yourself a Bluetooth scanner, I recommend a obdlink. It's 50 bucks but worth it. Check fuel trims and report back what they are. Long term and short term both banks. Also, look at data from the rear O2 sensors they are labeled as oxygen sensor b1s2 and b2s2... These monitor the gases post cat. If you don't have lean or rich codes, and the the 02 sensors don't seem to be moving at all then the sensors need to be replaced.
Thank you so much I have a scan tool but not a blue tooth
 

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08 CTS DI
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2,086 Posts
Hello Need some ideas thrown out here I’m getting the P0430 code. My local mechanic said that I needed a tuneup with that we also replace the valve covers with new ones. And the coils.
That’s all the problem with the check engine light not coming on for a while now it’s coming back I replaced cats
At a loss of what to do next .... O2 sensors ? Tried a cat cleaner but that only worked for a while
Coming from bank 2 is there anything I can try ? Any help you can give would be appreciated! It’s a 2009 CTS with 130k I haven’t had any real issues with car since purchase except leaking sun roof but I can live with that
It's too late now, but down stream O2 sensors should be checked thoroughly before replacing a catalytic converter on an affected bank. I just addressed this code on an LY7 vehicle and discovered it was caused by oil contamination of the O2 sensor plug upon working its way past the weather seal. The voltage range is small so it doesn't take much interruption of the signal to cause a problem. My most recent memory is that the down stream O2 sensors usually sit just above 700 mV at idle in the (my) CTS, with limited fluctuation range unlike the upstream sensors.
 

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1991 Sedan Deville 2004 Deville 2005 Escalade 2003 Deville T
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14 Posts
Discussion Starter #5
Get yourself a Bluetooth scanner, I recommend a obdlink. It's 50 bucks but worth it. Check fuel trims and report back what they are. Long term and short term both banks. Also, look at data from the rear O2 sensors they are labeled as oxygen sensor b1s2 and b2s2... These monitor the gases post cat. If you don't have lean or rich codes, and the the 02 sensors don't seem to be moving at all then the sensors need to be replaced.
The obdlink doesn’t work with iPhone can I get another ???
It's too late now, but down stream O2 sensors should be checked thoroughly before replacing a catalytic converter on an affected bank. I just addressed this code on an LY7 vehicle and discovered it was caused by oil contamination of the O2 sensor plug upon working its way past the weather seal. The voltage range is small so it doesn't take much interruption of the signal to cause a problem. My most recent memory is that the down stream O2 sensors usually sit just above 700 mV at idle in the (my) CTS, with limited fluctuation range unlike the upstream sensors.
thanks I love the car and as I said with the exception of the leaking sun roof car owes me nothing
I really would like to dispense with this issue since I’m a little OCD when the light comes on
 

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2011 CTS4 Performance 3.6
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Yeah.. if you can see live data with whatever too you have..see what the post cat 02 sensors are doing. If you have already replaced the cats, it kinda narrows it down.
 

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2011 CTS Coupe Premium
Orlando - We take orphans
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2,213 Posts
You can watch all O2 sensors and fuel trims on an Android phone or Tab for under $20 (Torque Pro and BT dongle). If only have Apple products, a 7 or 8" Android tab is under $50.

ps only the primary O2 sensors should have transitions. If the cat is working properly, the secondary (after the cat) O2 sensors should not move much from midpoint.
 

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Go ahead, blame me. Everybody does 🙄
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thanks I love the car and as I said with the exception of the leaking sun roof car owes me nothing
You dont have to live with a leaking sunroof, either...
 

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'09 CTS DI FE1 Luxury
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For ios try obd fusion or obd car doctor.
 

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1991 Sedan Deville 2004 Deville 2005 Escalade 2003 Deville T
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14 Posts
Discussion Starter #10
It's too late now, but down stream O2 sensors should be checked thoroughly before replacing a catalytic converter on an affected bank. I just addressed this code on an LY7 vehicle and discovered it was caused by oil contamination of the O2 sensor plug upon working its way past the weather seal. The voltage range is small so it doesn't take much interruption of the signal to cause a problem. My most recent memory is that the down stream O2 sensors usually sit just above 700 mV at idle in the (my) CTS, with limited fluctuation range unlike the upstream sensors.
579748
579749
579750
579751
 

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1991 Sedan Deville 2004 Deville 2005 Escalade 2003 Deville T
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Discussion Starter #11
I hope these are right
Thank you
Again
 

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08 CTS DI
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The down stream O2 values look good at a glance, next you should review the conditions under which the code is set for additional possible causes. The sensor may be delivering a problematic value under load conditions. You should also look at your long term fuel trims to make sure they are within normal range which I believe is below +15 to a little negative. If you have a graphing function, compare the graphs between the two sensors for similarity.

Now, about the catalytic converter replacement, are they OE, or aftermarket. If they are aftermarket it's a possibility that may be the cause. Most of the aftermarket cats I've seen look like a rushed, rush jobs compared to OE.
 

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1991 Sedan Deville 2004 Deville 2005 Escalade 2003 Deville T
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14 Posts
Discussion Starter #14
The down stream O2 values look good at a glance, next you should review the conditions under which the code is set for additional possible causes. The sensor may be delivering a problematic value under load conditions. You should also look at your long term fuel trims to make sure they are within normal range which I believe is below +15 to a little negative. If you have a graphing function, compare the graphs between the two sensors for similarity.

Now, about the catalytic converter replacement, are they OE, or aftermarket. If they are aftermarket it's a possibility that may be the cause. Most of the aftermarket cats I've seen look like a rushed, rush jobs compared to OE.
Oem
 
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