G’day bugeyeBS,
By power light do you mean the yellow check engine light? There is a method to read the stored codes by connecting two coloured plugs above the driver’s feet (green or black, I can never remember which one!), then putting the ignition to the ON position WITHOUT running the engine. It will flash long and short flashes for each code then repeat the sequence. The fuel pump should cycle on and off too.
Long flash (about a second) = 10; short flash = 1.
So — — — • • would equate to a code 32.
Write them down on paper, once you start looping through the same codes you know you have your list. If it’s only flashing a single digit code there are no stored codes, this one tells you what market the ECU was programmed for.
Then get on the net and find a code chart that’s not the chart for scanned codes with a device (typically a “P” code). This will point you in the direction of where to look first.
Disconnect the test connectors before starting the engine.
With the work you’ve done, did you disconnect the battery and let the ECU reset before starting up after the work you completed?
It could be worth getting a Haynes manual, they’re a good place to start for info and to develop your knowledge on your vehicle

There will be voltages and resistance values in these manuals for all sensors so you can test them all and find out what’s dodgy and what’s working fine.
Cheers
Bennie