An OBD II vehicle has an illuminated MIL and a stored DTC for "Catalyst Efficiency below Threshold" and both the pre- and post-catalyst oxygen sensor signals are fluctuating between 200 mV and 800 mV. What is the most likely cause?

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The Answer of An OBD II vehicle has an illuminated MIL and a stored DTC for "Catalyst Efficiency below Threshold" and both the pre- and post-catalyst oxygen sensor signals are fluctuating between 200 mV and 800 mV. What is the most likely cause?

An OBD II Vehicle Has an Illuminated MIL and a Stored