A method of diagnosing corrosion risk of a pipe or a pipeline buried in soil due to DC stray currents and/or AC voltages induced in the soil, comprising: i) providing a two-part metal probe (20,22,24) including a first probe part having a first metal element of a first size and a first specific resistivity, said first probe part constituting an exposed element, and a second probe part having a second metal element of a second size and a second specific resistivity, said second probe part being hermetically sealed and constituting a reference element, ii) burying said two-part metal probe (20,22,24) in said soil, iii) measuring the AC current flowing between said pipe or said pipeline and said two-part metal probe (20,22,24), iv) measuring the AC voltage between said pipe or said pipeline and said two-part metal probe (20,22,24), v) measuring the spread resistance based on said AC current determined in step iii) and said AC voltage measured in step iv) according to Ohm's Law, vi) passing a first excitation current through said first probe part and determining the voltage generated by said first excitation current across said first probe part for measuring the resistance of said first probe part according to Ohm's Law, vii) passing a second excitation current through said second probe part and determining the voltage generated by said second excitation current across said second probe part for measuring the resistance of said second probe part according to Ohm's Law, viii) storing said measurements provided in steps iii), iv), v), vi) and vii), ix) repeating said steps iii), iv), v), vi), vii) and viii) periodically, x) determining the corrosion of said first probe part based on the measurements performed in steps vi) and vii) according to a mathematical corrosion algorithm, and xi) diagnosing the risk of corrosion of said pipe or pipeline based on an empirical combination of the actual corrosion of said first probe part, said spread resistance determined in step v) and said AC voltage measured in step iv). i) providing a two-part metal probe (20,22,24) including a first probe part having a first metal element of a first size and a first specific resistivity, said first probe part constituting an exposed element, and a second probe part having a second metal element of a second size and a second specific resistivity, said second probe part being hermetically sealed and constituting a reference element, ii) burying said two-part metal probe (20,22,24) in said soil, iii) measuring the AC current flowing between said pipe or said pipeline and said two-part metal probe (20,22,24), iv) measuring the AC voltage between said pipe or said pipeline and said two-part metal probe (20,22,24), v) measuring the spread resistance based on said AC current determined in step iii) and said AC voltage measured in step iv) according to Ohm's Law, vi) passing a first excitation current through said first probe part and determining the voltage generated by said first excitation current across said first probe part for measuring the resistance of said first probe part according to Ohm's Law, vii) passing a second excitation current through said second probe part and determining the voltage generated by said second excitation current across said second probe part for measuring the resistance of said second probe part according to Ohm's Law, viii) storing said measurements provided in steps iii), iv), v), vi) and vii), ix) repeating said steps iii), iv), v), vi), vii) and viii) periodically, x) determining the corrosion of said first probe part based on the measurements performed in steps vi) and vii) according to a mathematical corrosion algorithm, and xi) diagnosing the risk of corrosion of said pipe or pipeline based on an empirical combination of the actual corrosion of said first probe part, said spread resistance determined in step v) and said AC voltage measured in step iv).