View Full Version : A4 1.8T code 3020 missfire on #2 cylinder

10-02-2008, 01:37 PM
I have a 1999 A4 1.8 T with 110K.
It started to miss on #2 cylinder and the dealer diagnosed it as a leaking valve cover gasket that was fowling the #2 spark plug. (This was not a correct diagnosis)
The quote was $1300 to replace the valve cover gasket, #2 coil, spark plugs and change the oil.
I changed the valve cover gasket, coil, and plugs in about 1 hour and it ran GREAT!!
The car ran withoutmissing a beat for about a week then #2 cylinder cut out, (misfired) again.
I swapped out the coil with #3 cylinder, but still #2 cylinder is not firing.
Compression is 105 PSI, fuel injectors all working, there is NO spark from #2 coil or the #3 coil, when it was swapped to #2 cylinder.
What could the fault be? [:/]

10-02-2008, 03:09 PM
idk alot about the electricals but did u make sure the wiring connector for the #2 cylinder isnt corroded and the contacts are still shiny that will create a good connection? I don't know what else would cause a misfire thats not electrical?

someone else will chime in here shortly im sure.
good luck

10-02-2008, 04:35 PM
IF your Ignition Amp (AKA Ignition control module) takes a crap it will normally only produce a misfire on cylinder #2. Your P0302 or VAG 16686 is what the ECM will store, it cannot sense a failure of the module/amp on it's own.

If you have a known good part to swap in, do that for testing purposes.

Otherwise, swap coils on #1 and #2. If the misfire moves from 2 to 1, you know the coil is at fault. If the misfire remains on #2 it could be the spark plug or the ignition amp(if you didn't replace it before).
This is of course presuming that you have compression and fuel. AEB's aren't know to be problem child's when it comes to that though.

I'd bet money on the ICM/ignition amp though. Start there. It's the goofy thing on top of your air box, mounted to a piece of aluminum heat sink.

10-08-2008, 02:58 PM
Thanks Josh, I am pretty sure that it is the Ign. control module.
I am changing it and will let you know.

10-08-2008, 02:59 PM
Thanks, I think you are right it is the Ign. control module. I ordered one and will let you know if it works.

03-15-2009, 07:21 PM
So... did this fix it? :)

I'm having the same problem on my 1.8t Jetta. I'm switching the coil packs around but it continues to misfire on Cylinder #2. (When I took it to the dealer they said to replace the valve cover gasket, which I did plus the spark plugs.)

03-15-2009, 08:00 PM
I dont think jetta's have an icm they are like the latter audis with them built into the coilpacks.