Abstract: A method of inspecting a ceramic wall-flow filter (1) for a vehicle exhaust system includes the steps of: a) providing a source (9) of heat energy suitable for heating material within the filter (1); b) applying heat energy from the source (9) to a first end (10) of the filter (1) to heat material within the filter; c) detecting infrared radiation (18) which has been emitted by heated material in the filter using a radiation detector (19) at the second end (11) of the filter (1) to form an image (24) of a pattern of emitted radiation, the pattern of emitted radiation providing an indication of the condition of the filter (1). Another aspect of the invention provides apparatus for use in the method.

Abstract: A method of inspecting a ceramic wall-flow filter (1) for a vehicle exhaust system includes the steps of: a) providing a source (9) of heat energy suitable for heating material within the filter (1); b) applying heat energy from the source (9) to a first end (10) of the filter (1) to heat material within the filter; c) detecting infrared radiation (18) which has been emitted by heated material in the filter using a radiation detector (19) at the second end (11) of the filter (1) to form an image (24) of a pattern of emitted radiation, the pattern of emitted radiation providing an indication of the condition of the filter (1). Another aspect of the invention provides apparatus for use in the method.