The light is on and the codes are PO155 and 300. We've changed the o2 sensors and the light has not gone off. The scan tool wouldnt even allow the code to be erased. We've done spark plugs, o2 sensors. what else can it be? We are having issues with pick up as well. The car is hard to get going and feels like you have to press the gas pedal so hard to get it going. Any advice?

 

plug in a scanner and check the o2 sensor voltages... more then likely you have a bad wire somewhere

look here
https://blazerforum.com/forum/diagno...plained-35155/