A method for inspecting a section of pipeline made of ferromagnetic material extending below a soil surface (S soil) along a longitudinal axis, the method comprising the following steps: • a) record, by means of magnetometers (M 1, M 2, M 3, M 4) arranged above the ground surface and the section of pipeline, first signals (S 1) representative of a first magnetic field (B E) combining the Earth's magnetic field and a magnetic field (Ft) induced by the Earth's magnetic field in the section of pipeline, the magnetometers being aligned along an axis substantially orthogonal to the longitudinal axis of the section of pipeline, and substantially parallel to the surface of the ground; • b) generate, by means of a first coil (C, C 1, C 1 ') carrying a first current (I, I 1, I 1 ') having at least a first value (I min, I v1) that is non-zero and a second value (I max, I v2) that is non-zero and different from the first value, a first additional magnetic field (F c, F c1, F c1 ') having a direction of polarization (P c, P c1, P c1 ') different from that (Pt) of the magnetic field (Ft) induced by the Earth's magnetic field in the pipeline section of pipeline; • c) record, using the magnetometers, second signals (S 2) representative of a second magnetic field combining the first magnetic field (B E), the first additional magnetic field (F c, F c1, F c1 ') and a magnetic field (F i, F i1, F i1 ') induced by said first additional magnetic field in the section of pipeline; • d) determine, from the second signals (S 2) and without using the first signals (S 1), third signals (S 3) representative of the combination of the additional magnetic field and the magnetic field induced by the said additional magnetic field in the section of pipeline; • e) compare the first signals (S 1) to first predetermined thresholds; • f) compare third signals to second predetermined thresholds; • g) Infer from the comparisons made in steps e) and f) that there is at least one defect in the section of pipeline. • a) record, by means of magnetometers (M 1, M 2, M 3, M 4) arranged above the ground surface and the section of pipeline, first signals (S 1) representative of a first magnetic field (B E) combining the Earth's magnetic field and a magnetic field (Ft) induced by the Earth's magnetic field in the section of pipeline, the magnetometers being aligned along an axis substantially orthogonal to the longitudinal axis of the section of pipeline, and substantially parallel to the surface of the ground; • b) generate, by means of a first coil (C, C 1, C 1 ') carrying a first current (I, I 1, I 1 ') having at least a first value (I min, I v1) that is non-zero and a second value (I max, I v2) that is non-zero and different from the first value, a first additional magnetic field (F c, F c1, F c1 ') having a direction of polarization (P c, P c1, P c1 ') different from that (Pt) of the magnetic field (Ft) induced by the Earth's magnetic field in the pipeline section of pipeline; • c) record, using the magnetometers, second signals (S 2) representative of a second magnetic field combining the first magnetic field (B E), the first additional magnetic field (F c, F c1, F c1 ') and a magnetic field (F i, F i1, F i1 ') induced by said first additional magnetic field in the section of pipeline; • d) determine, from the second signals (S 2) and without using the first signals (S 1), third signals (S 3) representative of the combination of the additional magnetic field and the magnetic field induced by the said additional magnetic field in the section of pipeline; • e) compare the first signals (S 1) to first predetermined thresholds; • f) compare third signals to second predetermined thresholds; • g) Infer from the comparisons made in steps e) and f) that there is at least one defect in the section of pipeline.