Plug Connection for Fluid Lines and Retaining Part for Such a Plug Connection

A plug connection (1) for fluid lines, comprising two intermateable first and second coupling parts (2, 3), which in an assembled state can be releasably locked together, a first outer radial flange-like retaining rib (21) formed by the first coupling part (2), and a second outer radial flange-like retaining rib (31) formed by the second coupling part which retaining ribs are adjacent in an insertion direction (S) and axial (X-X) in the assembled state, a retaining part (5) with an annular contour, which in a preassembled state can be axially and radially fixed and undetachably assembled on one of the first and second coupling parts (2, 3) and in the assembled state axially and radially encompasses the first and second retaining ribs (21, 31) of the coupling parts with at least one radially elastically moving retaining section (53) with a C-shaped axial section having first and second collars (52, 51), and

• the first and second collars (52, 51) of the retaining part (5) are configured with different sizes or shapes in such a way that the first collar (52), which abuts against the first retaining rib (21) releases the first retaining rib (21) of the first coupling part (2) with an outward radial elastic movement of the retaining section (53) from the assembled state, while the second collar (51) still engages at least in some areas behind the second retaining rib (31) of the second coupling part (3) against which it abuts.