Possible Fault Causes

corrosion in plug?) 1a. Repeatedly remove the plug and then FIRMLY insert it again 2. Electrical check of wiring 3. Check catalytic converter (FSD lean fault may be entered for the other bank) 4. Piston rings, injector valves, positive crankcase ventilation OK? FSD fault? Then continue there! 5. Replace wires or plugs on O2 sensors as indicated