P0420 after replacing Cat and both O2
#1
P0420 after replacing Cat and both O2
Hi folks, I'm a mechanic that is banging my head against a wall with two 2006 minivans. Both with 3.8L one a Grand Caravan and the other a Town and County. Replaced Catalytic Converter on both and replaced both (upstream and downstream) O2 sensors with NGK O2 sensors on both vans. I'm stumped with this one. Code comes back on both vans all the time. So much so that the Grand Caravan has the code set on the scanner but check engine light has become randomly on and off.
Anyone else out there seen this with the 06? or at all? I have no idea what to do on these and the dealer is being no help at all.
Thank you in advance,
ajcasper
Anyone else out there seen this with the 06? or at all? I have no idea what to do on these and the dealer is being no help at all.
Thank you in advance,
ajcasper
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#8
So, since the 1/1 was bouncing, can I guess that the upstream O2 sensor is in the outhouse?
#9
1/1 is the upsteam O2 sensor and it should fluctuate up and down. When the cat it warmed up and doing it's thing, the 1/2 sensor will kinda go to one side and be real lazy. That's what it should do. When the cat is bad, the 1/2 sensor will basically play follow the leader with the 1/1 sensor. Sometimes replacing just the downstream O2 sensor will cause the code because the old upsteam will have slowed down and with a fresh downsteam, the PCM gets faked out.
#10
1/1 is the upsteam O2 sensor and it should fluctuate up and down. When the cat it warmed up and doing it's thing, the 1/2 sensor will kinda go to one side and be real lazy. That's what it should do. When the cat is bad, the 1/2 sensor will basically play follow the leader with the 1/1 sensor. Sometimes replacing just the downstream O2 sensor will cause the code because the old upsteam will have slowed down and with a fresh downsteam, the PCM gets faked out.