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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 15133
Experience:  GM Grand Master Technician 2007. 14 years experience.
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2000 Chevrolet Blazer failed state inspection due to MIL

Customer Question

2000 Chevrolet Blazer failed state inspection due to MIL Commanded-On Fail, Three stored codes P0302-Cylinder 2 misfire detected, P0420-Catalyst System Efficiency Below Threshold (Bank 1), P0740 Torque Converter Clutch Circuit Malfunction. Thoughts?
JA: Have you seen the misfire code before? Has the car been stalling?
Customer: No. Previous checks would be the last code about the Torque Converter. The car will stall occasionally when cold (usually low on oil), but not in the recent three to four months.
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: I probably cannot fix this myself. I did take it to a transmission tech when the service engine soon light came on several months ago. He repaired, replaced everything necessary, but could not make the light stay off.
JA: Anything else you think the mechanic should know?
Customer: The first two stored codes are the first time I have seen them. The last code was the one popping up on diagnostics the previous three times.
Submitted: 2 months ago.
Category: Chevy
Expert:  Ryan Schott replied 2 months ago.

I would look at p0302 first as it can cause the other codes to throw, the first thing i would do i swap the coils from cylinder 2 to cylinder 3, clear the codes and see if p0303 comes up if it does its a bad coil if not i would then swap plugs and repeat, if nothing there you would need to test the injector next, let me know.