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2023 Nissan Z — catalyst efficiency code but car drives normally

CleanGeek210Community StarterJul 14, 20262023 Nissan Z PerformanceConnecticut
This started as a small annoyance and I finally decided to track it down. 2023 Nissan Z Performance, about 59,000 miles. A catalyst efficiency code came back after clearing once. The car drives normally and there are no misfire codes. Before condemning the catalytic converter, what sensor/data checks are worth doing? Interested in real owner experience more than guesses.
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6 replies

PistonPilotCommunity StarterCommunity StarterJul 15, 2026permalink
I'd want a measurement, not a hunch. Capture voltage while the 2023 Nissan Z is actually failing — after it restarts you've lost the clue. That's the branch I'd chase this week. Any freeze-frame data saved? Not trying to scare you — just skip the expensive first guess. No warning lights, which is why I'm documenting it.
CleanGeek210Community StarterCommunity StarterJul 15, 2026permalink
I went back under the 2023 Nissan Z and it only happens after a heat soak, not on a cold start. Trying not to diagnose from the couch.
HybridDetailer360Community StarterCommunity StarterJul 16, 2026permalink
That's a good start, but I wouldn't stop there. Swap the cheap/easy piece first on the 2023 Nissan Z and see if the fault moves. Don't erase codes until someone who can help has seen them. When does it actually happen? I'd rather pay for diagnosis than a second guess-repair.
CleanGeek210Community StarterCommunity StarterJul 15, 2026permalink
Checked the easy stuff on the 2023 Nissan Z and found one clue worth chasing before I book a shop. Only after sitting overnight so far.
DealHaulerCommunity StarterCommunity StarterJul 15, 2026permalink
If it were in my driveway, write temp, speed, and in-gear vs coast when the 2023 Nissan Z does it — then decide on parts. Save the big job until that test fails. Post the numbers (or the code) and people can get more specific. Heat soak after errands is the other window.
OldSchoolCommuter670Community StarterCommunity StarterJul 16, 2026permalink
Ask what changed right before it started. A pressure test beats staring at a dry driveway if the 2023 Nissan Z is losing coolant with no puddle. Save the big job until that test fails. I'd want that in writing, not as a promise. Make the next action something you can finish this week. I'll update if anything new shows up.
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