What does a P2423 code mean?

2009 NISSAN ALTIMA
130,000 MILES • 2.4L • 4 CYL • 2WD • AUTOMATIC
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MLYUHAS
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A solid service engine light just came on. About 10 months ago, I replaced the spark plugs and the o2 sensor I front of the catalytic converter. I had the big, more central, catalytic replaced 2 years ago. Could the oxygen sensor have gone bad? I also replaced the thermostat and coolant got everywhere because I’m an idiot..so maybe that ruined the new o2 sensor, but I don’t think it’d take 8 months to show. Help!
Aug 21, 2022 at 10:28 PM
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STRAILER
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DTC P2423
Symptom Descriptor
California Emissions

Probable Causes

Exhaust Tube
Fuel Injector
Hydrocarbon Adsorption Catalyst Under Floor
Ignition Timing Incorrect
Intake Air Leak
Spark Plug

You are okay, how does the engine seem to run? Also do you have any exhaust leaks? I don't think the oxygen sensor is bad. I have seen the MAF sensor cause this problem, you can try cleaning it but if that doesn't work replacement is required. This guide can help:

https://www.2carpros.com/articles/mass-air-flow-service

Check out the diagrams (below). Please let us know what happens.
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Aug 22, 2022 at 12:50 PM
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MLYUHAS
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My car is driving find. No idling issues at all. I replaced the upstream o2 sensor and soaring plugs about 10 months ago. I replaced the rear catalytic converter, the one connected directly to the exhaust, 2 years ago. I ordered a new MAF sensor that I’ll put in this weekend. I’m also waiting for my gas tank to empty to put some Cataclean it, but so far, no issues, just the solid service engine light and the multiples places I went all showed the P2423 code.
Aug 25, 2022 at 1:50 PM
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MLYUHAS
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There wasn’t an exhaust leak last year. They also tack welded a hold in my muffler, which still looks good.
Aug 25, 2022 at 1:52 PM
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STRAILER
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Okay, let me know what happens after the sensor. The exhaust leak will be before the primary oxygen sensor.
Aug 25, 2022 at 5:24 PM