Originally Posted by panhead
Ive bought new O2 sensors that were bad. If the truck runs without it in, return it. Most likely the O2 sensor is giving the PCM a wacky reading.
Readings from the sensors won't cause a no-start because the PCM is using open loop mode to calculate the fuel curve on start up. However, an internally shorted sensor of any kind could be pulling down the 5V reference circuit.
Judging by the fact you took the sensor out and the truck ran, I would think you have a plugged converter. This could also cause an O2 code to set.