I am getting a PO420 code for converter efficiency below threshold on my 2002 V6 Tacoma with 140k. I have installed new OE Denso plugs, wires and ran several tanks of premium with fuel system cleaner but the code still persists. I have replaced the rear 02 sensor and have checked and the front one is working correctly. It is only 3-4 years old. Both are OE Denso's. Does the fuel trim look ok in the picture? Any helpful suggestions?
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