Opel astra H 1.6 16v 2006 battery and check engine light

Question

I have an Astra H 2006 1.6 16V, and battery light and "check engine light" came on so I took it to the mechanic (in Sweden). They said it was an alternator problem (which I also thought to be the issue since I used a voltmeter and recorded 11 V on the battery with the engine at idle), they changed the alternator and everything seemed fine for a few hours.

Then the two lights came on again and now a strange thing happens: if I measure the voltage on the battery it gives around 10.3 V, but in the "secret" menu on the screen it shows 14.6V with the engine running, and about 11V with the engine off. Furthermore, it also seems to misfire (rpm does not stay constant, but wiggles) at around 2200 rpm in all gears (very noticeable in 5th gear when I set the cruise control to 80kmh).

The fault codes found with the pedal test are: 030100 030200 030300 030400 031300 031400 062104 111505

Does anybody have an idea of what's causing these issues?

Thanks in advance!

Answer 1

The alternator cannt charge the battery if the cable is dropping valtage due to corrosion/cuts-check each end of red lead and also earths for voltage drop. Its what should have been checked before a new alternator is installed

Answer 2

The codes starting with 0 are generic and you can google them, just take the first 4 digits (or drop the last two). It looks like yours are saying random misfires on all cylinders due to not enough fuel and problems with alternator. I would lodge a complaint with the garage that replaced the alternator.