I'm new to the forum, and need some help. I've got a 03 a4 1.8t that won't start. I plugged in my obd II code reader and got p0688. I checked for spark and there was no spark..I checked for fuel and its got that.. So I went underhood opened up the box where the ecu sits and replaced the relay with 219 written on it, because according to what I've looked up p0688 refers to that circuit... Still nothing.. the car turns over but won't fire up. So after further homework I saw that the connectors from the main harness to the coilpacks were looking terrible, when i opened up the rubber boot going to the connector, all the wires inside were frayed and green (should be copper not corroded right?). Now my question is this, I'm assuming I need to replace the engine harness going to the coils.. Is this the solution or is there another common sensor that'll cause this problem? I was thinking crank sensor maybe but then I should get that fault code.. which I'm not Really need help. thanks.