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How To Test The 1.8L VW Ignition Module

A bad ignition control module causing a misfire condition (and one of the following diagnostic trouble codes: P0301, P0302, P0303, P0304) is a problem I have encountered quite a bit on the 1.8L VWs.

In the beginning, I would diagnose the issue with my oscilloscope (which is the most accurate way of doing it, but a little more time consuming). But,. like I mentioned before, since this is a very common problem with this type of ICM in the 1.8L VWs, I was able to forgo the oscilloscope and test them the way I've described in this tutorial with a lot of success.

The most important things to remember (and to successfully diagnose the issue) is to:

  1. First: Identify the misfiring cylinder with a cylinder balance test (even if you do have a misfire code).
  2. Second: Test for spark with a dedicated spark tester.

Hopefully this tutorial helped you nail down the misfire problem, if it was being caused by a bad ignition control module or a bad ignition coil.

If you found this info useful or have something to add for the benefit of anyone else who might be having a similar issue/problem, you can use the contact form below to get in contact with me.

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Volkswagen Vehicles:

  • Beetle 1.8L
    • 1999, 2000, 2001
  • Golf 1.8L
    • 2000
  • Jetta 1.8L
    • 2000
  • Passat 1.8L
    • 1998, 1999

Audi Vehicles:

  • A4 1.8L
    • 1999, 2000
  • A8 3.7L
    • 1997, 1998, 1999