bang-bang

[johnny_quattro]

Car started like a bag of lumpy potatoes tonight, like it was missing on one cylinder. Performed a quick OBD check and it shows the following:

P1231 - Fuel injector Cyl.7 Short circuit to ground
static
P0154 - O2 Sensor Circ.,Bank2-Sensor1 No Activity Detected
static

Hopefully a quick question and a quick answer:
Is this a coil pack gone bad or is my injector dicky? Or something else perhaps.
When attempting to clear codes, it seemed to have a hiccup when communicating with the engine control unit. Cleared codes on 2nd attempt so perhaps that's a bum steer.

Problem seemed to clear after the car warmed up and there was some 'spirited' driving. Any suggestions/advice, as always, gratefully received.
Cheers

Johnny G