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The seized one is drivers side wouldn’t that be a 420 code the one that keeps coming up is 430should have looked at cat temps 400c instead of 3 minute run time
i think your seized o2 is the problem one
went from a reasonable reading to lean
Try it when they are warm (as in 50-60°), (not hot). They will be easier. Can be near impossible when cold sometimes.I replaced with genuine sensors but as u say swap passenger to drivers the p0430 is passenger side issue also I tried to do that pryer to paying for a second o2 sensor and I can’t remove drivers side front sensor even with the right tool as it’s jammed
Your Comment as -As others have said, this code relates to what the post-cat (rear) sensor detects. It has nothing to do with front O2 sensors.
Explanation:
The cat's sole job is to remove any unburned fuel and CO (carbon monoxide) remaining in the exhaust and convert it into carbon dioxide (CO2) and water. To undertake this chemical reaction, the cat needs oxygen. It scavenges the remaining oxygen from the exhaust during lean-burn periods (when you see the front O2 sensor at low-voltage).
It then uses that oxygen to convert (oxidise) the CO. The signal coming from the rear sensor should be more-or-less flatline if the cat is working properly. It releases oxygen during rich conditions, and it accumulates oxygen during lean conditions. All this can happen multiple times per second.
The post-cat sensor's job is to monitor the catalytic converter's oxygen storage capacity.
The ECU is programmed to actively test the catalytic converter only under very specific operating conditions - this includes parameters such:
Engine at normal operating temp
More than 1/4 tank of fuel
No DTCs in the ECU
Less than 30% throttle
Above 70kph
After 7 minutes of stable conditions etc
...so generally during highway driving conditions. This explains why you may only get the check engine light sporadically.
This is a very complicated topic.
Google 'Catalytic converter monitor drive cycle' to learn more.
Either you have a buggered sensor or wiring, the cat is not working properly, or you have an exhaust leak (air entering) in the exhaust before the cat.