The causes of a P0204 engine light code could be any of the following:

Bad injector. This is usually the cause of this code but doesn't rule out the possibility of one of the other causes

Open in the wiring to the injector

Short in the wiring to the injector

Bad PCM

I started by switching injectors around and by making sure the harness connections were clean.
It was still throwing the code for injector #4 after switching them around... Bought another harness to replace the current one, but as I tried to disconnect the old harness I found something interesting.

Looks like the wires rub against the A/C line and this isn't the actual injector harness. It's the wiring that goes to the PCM, which is a PITA to replace... Luckily putting electrical tape around it did the trick... This isn't the first time I hear about wiring rubbing against A/C lines so I would suggest you check yours too

I'll keep you guys updated.

 

Interesting, did you throw some wire loom on it to help with the rubbing?

 

Yea of course . Luckily I had some in the trunk