2002 Blazer 155K o2 and Cat monitors not setting, no error codes
I have been doing some research and not sure what to next. My OBD scan tool shows activity on all 3 o2 sensors. I did change the downstream o2 sensor(after the cat) because of a heating element error code and replaced it with a OEM part about a year ago. I have heard that maybe the Cat could be bad or maybe that my gas gauge fluctuates ( goes from full to empty regardless of how much gas is in the tank, sometime whips back and forth while driving) that may cause the ECM to not let the monitors to set. According to the book it expects 1/4 to 3/4 in tank. Before I start changing anything else I though you might have a though on what to do next.
Thank You and I appreciate any advice you might have.
West Babylon NY