Resistance values for AF sensor and O2 sensor.

[paulsz]

The short printout from P0420 reads:
Probable cause:
1. Air leak in exhaust before rear HO2S (Heated oxygen sensor) Bank 1
2. AF sensor error
3. Fuel system fault
4. Faulty catalytic converter

Wow, I am so glad that they did not list 5. Driver's socks may need washing.

I am not a mechanic, don't have diagnostic equipment other than an electric multimeter. AF sensor reads 2.1 Ohms, O2 sensor read 14.2 Ohms. Is this a good starting point? Thanks for any constructive input.

Camry 2002, 4cyl. Drives very well, did not notice a drop in fuel efficiency.

[paulsz]

Found a 2002 repair manual on scribd which lists Oxygen sensor at 11-16 Ohms and AF sensor at 1.8-3.4 Ohms (at 20deg C). So it looks like mine are in range.

So that leaves air leak before bank 1, fuel system fault, or faulty cat.