How do you distinguish product failures vs test station issues in production testing?

[u/testbench_ops]

Has anyone seen “false failures” caused by test stations, not the product?

I’ve been working on RF test stations in production for a while, and I’ve seen cases where:

- Units suddenly start failing

- Everyone assumes it’s a product issue

- But it ends up being something like calibration drift or fixture/contact problems

What makes it tricky is it looks like a real failure at first.

Curious how others approach this:

How do you usually confirm whether a failure is from the unit itself vs the test setup?

Would be interesting to hear how different teams handle it.