Having trouble with my 2002 4X4 V6. Very rough idle, poor fuel mileage. Ive researched some of the codes through swart's posts and learned a lot. Yet I am wondering if anyone has had codes from the O2 heater circuit before, they are all through a scan tool, and have to do with the O2 Heater Circuit except one is PO128 and PO452. One mechanic before said one of the three O2 sensors were bad but wondering how to find the one that is or a direction from here. Thanks a lot for any knowledge.

 

P0128 - Engine coolant fails to reach preset target temperature
P0452 - Evaporative Emission Control System Pressure Sensor Low Input

What code(s) were you getting on the O2 sensors?