Patent ID: 8342019

Claim:
A probe unit for taking a sample of an exhaust gas flowing in a duct, the probe unit comprising: a gas sensor having an inside, and having multiple gas introduction bores for introducing a gas into the inside of the gas sensor; a sensor holder inside of which the gas sensor is held and that is arranged to be inserted inside of the duct so as to introduce the exhaust gas flowing in the duct into the gas sensor; a calibration gas flow channel that is arranged in the sensor holder and that has an opening at an inner surface of a side wall, surrounding the gas introduction bores of the gas sensor, of the sensor holder so as to supply a calibration gas to the gas sensor; and a guide groove that is arranged continuous to the opening of the calibration gas flow channel and arranged on the inner surface of the side wall along an arranging direction of the multiple gas introduction bores to face the multiple gas introduction bores.