I just had my 1999 Astra G 1.6 16v serviced and the next day leaving a friends house the ECU light came on, upon doing the error test I got two reported codes

0200 isnt listed in the codes I have seen but googling forums showed "injector circuit malfunction" or "Injector Circuit is open"

0135 is Heated Exhaust Gas Oxygen Sensor

Now the funny thing is that reports I have seen of 0200 have been either the car not starting or performance degradation of which on my drive home I had none of.

In otherwords no noticeable difference in any car function yet two error codes, I am going to take it back to the service center as soon as possible and am using a different car in the meantime but I would much appreciate you guys input. I would also like to know just how much these would be to fix if they turned out to be actual problems and not just a glitch or sensor cable come loose.

Thanks in advance

EDIT: 0135 issue, the evening was a rather cold one, I dont suppose the car could have misread the sensor not working and I heard that the error codes dont clear themselves ?

EDIT 2: Just did some more testing 0135 is causing the car to run rich, still no signs of 0200 though.