A CAT sensor may appear to have the same threaded end as the removed part and still be unsuitable. Diameter is only one feature of a threaded connection. The thread form, pitch and intended sealing arrangement must agree with the specified application; the electrical connection is a separate check.
Ask for the complete thread designation
A rough outside-diameter measurement does not name a thread. Nor does a photograph establish its pitch reliably. If the specification is available, copy the complete designation, including the system and pitch information, instead of shortening it to a number that resembles the measured width.
Keep measured observations distinct from documented specifications. A workshop measurement can help identify a discrepancy, but it should not be presented as the manufacturer's thread definition. Where the required designation is unknown, use the original part reference and application information to obtain it.
The seal belongs in the comparison too
Thread engagement and sealing are related but different matters. The design may use a specified sealing surface or seal rather than relying on the threads alone. WIKA's explanation of pressure-sensor wetted parts includes seals and gaskets among the components that can contact the medium.
For a purchase comparison, note the documented connection and sealing arrangement. A photograph of the threaded portion alone can leave out the shoulder or seal location. Request a view that includes those features, without assuming that a loose seal found beside the sensor belongs to it.
This does not identify the seal material or installation procedure. Those requirements come from the specified component and application. Do not select a sealant, tightening value or substitute seal from the visual resemblance between two sensors.
A matching plug leaves other questions unanswered
The electrical connector can be compared for its shape, keying and contact arrangement. That comparison does not establish the signal type, supply requirements or measurement range. These must be confirmed separately against the required sensor specification.
WIKA's pressure-sensor overview distinguishes measurement range, pressure connection, output signal and electrical connection. These are general selection dimensions, not a cross-reference for a CAT part. Use them to identify missing information in an offer, not to infer an unlisted replacement.
For example, a supplier may confirm that the connector housing matches while leaving the required range unanswered. That is a partial response. Keep the range question open rather than recording the whole sensor as approved because one visible feature agrees.
Photograph enough of the connection to make it useful
A side view should include the thread, its end and the adjacent shoulder. A separate connector view should show the locking and keying features. Keep a full-body image as well, so the close-ups can be traced to the same item.
If measurements are supplied, state where they were taken. Overall sensor length and the length of the threaded section are not interchangeable. Perspective can also make an angled photograph misleading; use an actual recorded measurement rather than estimating a dimension from screen size.
Keep any adapter visible in the record. A sensor photographed with an adapter attached may conceal the sensor's own connection.
Compare the offered specification before ordering
Use the confirmed CAT part reference as the starting point, then resolve any difference in the proposed alternative. Ask the supplier to state the connection specification and electrical characteristics relevant to the identified application. A phrase such as 'same size' is too vague to settle those requirements.
Do not trial-fit an uncertain threaded sensor to decide whether it is correct. Apparent initial engagement is not application approval. Any installation belongs with the proper equipment procedure and the person responsible for that work.
The related guide to sensor body length covers measurement boundaries in more detail. Browse CAT parts once the required component is identified. The order should preserve its full reference and any agreed substitution conditions, rather than describing it only by thread size and connector colour.
