of a good O2. An additional more conclusive test is to read the voltage swings because you can get 5 blinks/10sec and still have poor voltage readings. On voltage look for about 0.9v on the high and about 0.1v on the low with 5 blinks/10sec at 2000 rpm warmed up.
Also check the ohms on the heater wire side of the O2. Disconnect the O2 connector to do this and probe the connestor side that is wired to the O2 sensor. If not in spec the O2 will not warm up quicker and that will effect readings sent to the ECU till the O2's.
