TSB: Frozen Blazer

This bulletin applies to 2020-2025 Chevy Blazer vehicles. DTC P04FB may be set as failed current or history. The cause may be moisture or condensation freezing in the crankcase pressure sensor assembly. If you encounter this DTC in below-freezing temperatures, remove the PCV/crankcase pressure sensor and hose assembly and inspect for frozen moisture in the sensor and hose. If frozen moisture is present, allow the sensor and hose to thaw and drain out. Use a combination of light compressed air and a shop towel to remove any residual moisture. There is no need to replace the sensor or hose.