Gas sensor element and manufacturing method thereof

A method for manufacturing a gas sensor the gas sensor comprising:

• an oxygen-ion conductive solid electrolyte body;
• a measuring electrode and a reference electrode provided respectively on a surface and another surface of the solid electrolyte body;
• a signal lead connected to the measuring electrode, the signal lead part extending to a base end side of the measuring electrode;
• a first ceramic layer covering the signal lead part from an opposing side to the solid electrolyte body;
• and
• a second ceramic layer mounted between the signal lead part and the solid electrolyte body,
• wherein:
• any one metal or an alloy of more than one metal selected from a group consisting of Pt, Au, Ag, Pd, Rh, Ni and Ir, is laminated to an outer surface of the second ceramic layer by electroless plating in forming the signal lead part;
• and
• the second ceramic layer has formed therein a dyeing section abutting the signal lead part,
• the dyeing section comprising a part of the metal or the alloy that has been dyed in the second ceramic layer.