Bosch BIP373 Coil Driver Mod Kit
Bosch BIP373 Coil Driver Mod KitBosch BIP373 Coil Driver Mod Kit

Bosch BIP373 Coil Driver Mod Kit

5 out of 5 based on 2 customer ratings
(2 customer reviews)


In stock

Product Description

The power transistor that Bosch uses in their own ECUs is now available to you! This is a ‘mod kit’ for installing a BIP373 in a Megasquirt, or replacing an older or damaged VB921 with the much improved BIP373. This kit includes a Bosch BIP373, mica insulator, mounting hardware, and a 330 ohm resistor (used for MS1/Extra and MS2/Extra mods).

These are almost a drop-in replacement for the (long ago discontinued) VB921, except that they must be installed with a mica insulator as they have a metal backed case. Other than that, they work with exactly the same circuits as the VB921. We have a page that goes into more detail about these transistors here. These have held up very well in our tests, even when we’ve deliberately tried to break them. But like a VB921, they still provide current limiting to protect the other components of your ignition circuit.

We’ve tested these with MS1/Extra, MS2 standard code, and MS2/Extra.

Note: For the DIYPNP, use part number DP_BIP373-K.

2 reviews for Bosch BIP373 Coil Driver Mod Kit

  1. 5 out of 5


    Great product and it really works.

  2. 5 out of 5


    I have used this mod before and it really do away with any trouble you maybe having with the ignition on GM. It’s a great product and will use them from now on on any MS that I install.

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Where do I install the transistor in the MegaSquirt?

  • You can mount them to an extra heat sink above or below the main heat sink, or bolt them to either the case lid or endplate.

Can I use them with an MS3X?

  • The MS3X spark outputs are hard wired directly to the DB37, and a case with an MS3X inside is already fairly crowded. We recommend using an external ignition module with the MS3X like our QuadSpark four channel module instead. You can, however, install a single BIP373 on the main board for one channel direct coil control.