BMW used a lot of these Bosch style connectors on their cars during the 80s and 90s. Below are a 5-pin female and 2-pin male style.
Unfortunately, they decided to permanently lock the connectors which prevents them from being de-pinned. Let me show you what I mean.
Circled in red you can see where they heated up the connector and pressed down into the cavity where the wires are. This prevents the wire from being evacuated. Even if you have the correct de-pinning tool, the wire will get stuck and not back-out all they way.
Here you can see where that little nub is.
The best fix for this is to replace the connector entirely. The connectors I sell are not locked. I also sell a de-pin tool that will work on the connectors I sell.
Bosch style 4 pin female connector kit
Bosch style 5 pin female connector kit
The 4- and 5-pin female kits include a housing, female crimp terminals and individual wire seals. They are supplied without wire, a rear rubber boot or a mating male connector. Compare the mating face, keying and latch with your original connector before ordering.
Need a custom BMW wiring harness?
Falk Manufacturing builds custom and small-run BMW adapter harnesses. The M20-to-M50 TPS adapter harness shown here is one example of a clean, reversible connector conversion that avoids cutting the original engine harness.
Have a different connector conversion or harness-repair project? Email info@falkmfg.com with the vehicle year and model, engine and ECU information, clear photos of both connector faces, and any available pinout information. I’ll review the project and do my best to develop a solution for you.
View the M20-to-M50 TPS harness example →
4 comments
@Shane, an update as of October 15, 2026: I now offer a 5-pin Bosch-style female connector kit with the housing, five female crimp terminals and five individual wire seals. You can find it here: https://falkmfg.com/products/5-pin-bosch-style-female-connector-kit
The kit is supplied without wire, a rear rubber boot or a mating male connector. Before ordering for your E30 M3 AFM, please compare the mating face, keying and latch in the product photos with your original plug. If you would like help checking it, email clear photos to info@falkmfg.com.
This updates my earlier reply about not being able to source the 5-pin version. Thanks for asking!
Jacob, Falk MFG
@Henry, if the connector was heat-staked down like the examples I show in red, the best thing to do is to cut the wires close to the connector and replace it with the 2 or 3 pin options I sell.
@Shane I have not been able to find the 5-pin version. If you really wanted to salvage the 5-pin you could try and drill-out the portion I show where they heat-stake it. Then the pins wont be permanently stuck and you can get them out with the de-pin tool I sell.
Depin tool: https://falkmfg.com/products/bosh-style-connector-de-pin-tool
When replacing connector you have to just cut off wires or how do i keep wires and remove connector ?
Can you provide the Bosch 5 pin connector and pins as used for the plug to the AFM on the E30 M3 as my wiring has broken close to the plug and I can’t get the wiring pins out of the plug. Thanks, Shane