Where is the engine ECU siuated on a VW Golf GTI 1999 Mk 4

Question

I it under the dashboard or oin the engine compartment.

Answer 1

Your ECU in located under your cowl.  The cowl is the plastic piece that runs across the bottom of your windshield you have to remove your windshield wipers to remove the cowl. the ECU is right in the center with two big connectors on it.  Hope this helps, good luck.