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2006 CTS ,2004 Mazda RX8 , 2000 Chevet express conversion van
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26 Posts
Discussion Starter #1
I have a 2006 CTS 3.6 . Getting the bugs out of it after an engine swap. Along with computer issues .still working on that ECM comes this week . I had upstream O2 sensor on bank one and a down stream sensor on bank 2 . I replaced those with new sensors . Now I am getting 420-430 codes . 0420 - Catalyst System Low Efficiency ,P0430 - Catalyst System Low Efficiency Bank 2 ..............
Question as it is recommended to replace O2 sensors in pairs would you replace the other two sensors before replacing the cat converters ? If that does not solve the 420-430 codes then replace the two cats ???
Anyone experience this ?
Thank you for your imput !
 

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2006 CTS ,2004 Mazda RX8 , 2000 Chevet express conversion van
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26 Posts
Discussion Starter #3
UPdate I had a buddy come over with a scanner and he was able to go through all of the computer modules and see what was going on . Problems Key would not turn engine over , TC light on , no heat , few other things . Once car is jumped (purple wire to positive terminal ) she starts and runs fine and will start by the key for 20 min . We could see that key was functioning proper ,fuel passcode was being given , , anti theft module was functioning as it should . We could determine that computer was not activating when we turned the key to start . Conclusion that ECM was defective . I have another computer here I bought off ebay . I installed it but with out it being programmed to my car it would not work ....
I was recommended a repair shop that the mechanics are all certified and most are x cadillac tech. they can reprogram computer for me ..thank god at a reasonable cost ...
 

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2005 3.6L AY6 stock
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31 Posts
Agree, I had the same symptom with my ECM. I paid $50 to a junkyard for an ECM and $150 to the dealer to program it.
 

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2019 Silverado LD | Blacked Out
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29 Posts
Few years back we picked up an 05' with a blown engine for someone here. (Threw the chain out the cover and dented the hood... craziest one to this day). Anyhow, same deal the car sat for a bit and after it was fixed up engine-wise we ended up replacing the ECM for the same no start issues. They don't like to sit...

If you'd like a price on some Converters... shoot me a message or email. Don't waste your time with aftermarkets, they only create headaches. Can't hurt... the quote costs nothing!

Last 8 of VIN in the message please

[email protected]
 

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2006 CTS ,2004 Mazda RX8 , 2000 Chevet express conversion van
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26 Posts
Discussion Starter #6
I ended up replacing the computer with a new one . Come to find out computer was not the orgional one ! ??? I boulght one for a 100 and paid 17x5 to have it reflashed , never could get it to recognize the key. It starts now and I still have the 420-430 codes to replace the cats ..... will order parts this week , love the car !!
 

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Registered
2006 CTS ,2004 Mazda RX8 , 2000 Chevet express conversion van
Joined
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26 Posts
Discussion Starter #7
Few years back we picked up an 05' with a blown engine for someone here. (Threw the chain out the cover and dented the hood... craziest one to this day). Anyhow, same deal the car sat for a bit and after it was fixed up engine-wise we ended up replacing the ECM for the same no start issues. They don't like to sit...

If you'd like a price on some Converters... shoot me a message or email. Don't waste your time with aftermarkets, they only create headaches. Can't hurt... the quote costs nothing!

Last 8 of VIN in the message please

[email protected]
You have a set of catalytic converters /Price please ......I have replaced all 4 O2 sensors
 
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