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2013 Chevrolet Silverado 1500 — catalyst efficiency code but car drives normally — Queens owner question

GaragePilotCommunity StarterDec 2, 20252013 Chevrolet Silverado 1500 LTQueens
2013 Chevrolet Silverado 1500 LT, about 170,000 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?
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11 replies

TowCommuterCommunity StarterCommunity StarterDec 2, 2025permalink
If it were in my driveway, write temp, speed, and in-gear vs coast when the 2013 Chevrolet Silverado 1500 does it — then decide on parts. If the cheap test changes it, stop and reassess. If they can't show the line item, I assume it's hiding. If the story changes I'll post the new data.
WrenchCollectorCommunity StarterCommunity StarterDec 2, 2025permalink
I wouldn't throw parts yet. If a shop can't duplicate it on the 2013 Chevrolet Silverado 1500, bring a video plus freeze-frame data, not just a story. If the cheap test changes it, stop and reassess. No need to make it theatrical. I'm keeping receipts and dates in one folder.
RustBeltDad777Community StarterCommunity StarterDec 2, 2025permalink
I'd want a measurement, not a hunch. If a shop can't duplicate it on the 2013 Chevrolet Silverado 1500, bring a video plus freeze-frame data, not just a story. Save the big job until that test fails. Happy to compare notes if your setup is different. Checking again after work.
HighwayDIYerCommunity StarterCommunity StarterDec 3, 2025permalink
I'd want a measurement, not a hunch. A pressure test beats staring at a dry driveway if the 2013 Chevrolet Silverado 1500 is losing coolant with no puddle. Save the big job until that test fails. Did the worksheet show tax yet? This is me being the wet blanket on purpose.
WrenchCollectorCommunity StarterCommunity StarterDec 3, 2025permalink
Start with the test that can prove you wrong. A pressure test beats staring at a dry driveway if the 2013 Chevrolet Silverado 1500 is losing coolant with no puddle. Don't erase codes until someone who can help has seen them. No need to make it theatrical. This is me being the wet blanket on purpose.
GaragePilotCommunity StarterCommunity StarterDec 3, 2025permalink
I went back under the 2013 Chevrolet Silverado 1500 and it only happens after a heat soak, not on a cold start. Trying not to diagnose from the couch.
SunBeltCamper650Community StarterCommunity StarterDec 3, 2025permalink
This is usually cheaper to test than to guess. A pressure test beats staring at a dry driveway if the 2013 Chevrolet Silverado 1500 is losing coolant with no puddle. Save the big job until that test fails. That's the whole play. Make the next action something you can finish this week. Doing the boring step first on purpose.
DailyTraveler76Community StarterCommunity StarterDec 4, 2025permalink
Agree — and I'd add this: Capture voltage while the 2013 Chevrolet Silverado 1500 is actually failing — after it restarts you've lost the clue. Don't erase codes until someone who can help has seen them. On “catalyst efficiency code but car drives normally,” that was the fork that mattered for me. This is from a 2013 Chevrolet Silverado 1500 in Queens with 170,000 miles. Verbal 'we'll take care of it' is not a plan. Only after sitting overnight so far.
GaragePilotCommunity StarterCommunity StarterDec 3, 2025permalink
Checked the easy stuff on the 2013 Chevrolet Silverado 1500 and found one clue worth chasing before I book a shop. I'll poke at it this weekend.
DealGalCommunity StarterCommunity StarterDec 3, 2025permalink
Start with the test that can prove you wrong. Swap the cheap/easy piece first on the 2013 Chevrolet Silverado 1500 and see if the fault moves. Save the big job until that test fails. Stop there until you know. Cold start is when I can actually reproduce it.
HighwayDIYerCommunity StarterCommunity StarterDec 4, 2025permalink
That's a good start, but I wouldn't stop there. Move a coil or plug on the 2013 Chevrolet Silverado 1500 if it's cylinder-specific and see whether the code follows. That's the branch I'd chase this week. When does it actually happen? Make the next action something you can finish this week. Checking again after work.
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