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Q: Can't pass emissions.

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My car's Check Engine light comes on and a cannot pass an emissions test. I had it diagnosed and it said the catalyst efficiency was below threshold in bank 2. The mechanic said the probable causes were a leak in the exhaust before the converter, a faulty heated oxygen sensor in bank 2, a rich fuel to air ratio, or a faulty catalytic converter.

A: The system should be scanned and the 02 sen...

The system should be scanned and the 02 sensors checked when the system is enriched to see if the sensors respond correctly. You could just have a defective sensor or a convertor that is bad. Only these tests can determine which one is the cause.

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