on November 9, 2009, 5:52 pm, in reply to "Toyota Celica 1.8 2002 ZZ1 - Fault code P0141 Bank 1 sensor 2 #"
Had it back in this afternoon and the customer said the MIL came back on the next day
I checked the voltages sensor side similar to Daves waveform
Yellow = Front Sensor
Green - Rear Sensor
Engine Hot
Key Off
Key On....and battery voltage
Slight dip when starting
Full voltage present when running
I then checked with Amp Clamp (Pico)
0.5 amps at front sensor
0.0 amps at rear sensor
So check resistance again and this time
15 ohms at front
0 ohms at rear
So I think the sensor has now completely failed
New sensor on order from Toyota £158:00 plus vat
Thanks again for all the help, I certainly know more about 02 heater circuits now 
Peter
