The exhaust cam hal sensor is only there to prevent people from easily changing the valve timing. I works too don't it. Look for things like this to become very popular in years to come, as a means to ensure emissions aren't messed with. It's being called enhanced tamper resistent OBDII, but it sure works to deter the aftermarket.
It can be defeated by locating a hal near the crank trigers and setting up some dummy trigers for it that match the pulley trigers. But that would be a PIA.
Best fix is to spring for a stand alone, and piss on OBD altogether. Problem is thats around 2 G's, and a ton of wiring.