my car, since my last post, has been running just fine ever since, thanks for all the positive comments above. um, if I'm not mistaken, the heater circuit is controlled by the ECU, and is based on operating temperature. they come on when the car is cold, according to the coolant system temperature read by the ECU, and are turned off upon reaching operating temperature, and possibly in combination with reading catalytic efficiencies being normalized. one way would be to check that voltage is actually being provided to the heater circuit at one of the oxygen sensors when cold, and when the car is warmed up, to see the provided voltage turned off. if the code is only being set because the oxygen sensors are not warming up quickly enough, as the car warms up, makes me think the associated relay and the wiring itself be at fault. start with finding that relay and testing it and primary voltages being existent and whether the relay is snapping on and off as it should. the oxygen sensors you replaced should be the 4 wire type, two for the sensor and two for the heating circuit. I know it's possible to use 2 wire sensors, but that heating circuit being designed into the whole thing is not easy to get around.

 

Thanks, They are 4 wire o2 sensors and brought good quality not cheap stuff from Ebay, I was thinking that there was a separate heat sensor for the switching on /off the heaters and thought starting there if I could Identify the location? I did read that the sensor is in the bottom of the radiator but not sure if it was this model or not. I will keep looking and try to find the relay as well. cheers