Need help with a few codes.

16795
P0411 Sec.Air Inj.Sys. Incorrect Flow Detected

[B]16538
P0154 O2 Sensor Circ.,Bank2-Sensor1 No Activity Detected

17605
P1197 O2 Sensor Heater Circ.,Bank2-Sensor1 Electrical Malfunction

16684
P0300 Random/Multiple Cylinder Misfire Detected

16687
P0303 Cyl.3 Misfire Detected

16500
P0116 Engine Coolant Temp.Circ Range/Performance (A hose came loose and all the coolant was lost. That's fixed)


I'm thinking the problem is either the postcat 02 sensors or the maf cause the gas mileage has decrease noticeably. Plus I've had the same code "electrical malfunction" code for both postcat sensors. But what could cause the misfire. It only happened once when I lost the coolant and the car was beginning to overheat. The car runs smooth as usual.

 

[b]16538
P0154 O2 Sensor Circ.,Bank2-Sensor1 No Activity Detected (driver's side before cat)
Thats the cause of the poor fuel mileage, the CTS sensor also causes poor fuel mileage.
You don't have any codes for the postcat O2 sensors, just pre-cat O2 sensors.
The misfire can also be caused by a bad CTS sensor.
The secondary air pump fault is either a bad vacuum line between the combination valves on the back of the head or the SAP pump is bad most likely.

 

so ignore the SAP code for now and do the CTS and 02 sensor.

 

I changed the cts about 25k ago when the temp gauge was erratic. Would it go bad so soon? I'll blame the misfire on the cts being that there was no coolant present and the engine was over normal temp. I've pulled the same "electrical malfunction" codes for both postcat sensors a few times in the past 6 months, this is the first I've seen one for the precat. The sap pump works fine, but I have noticed it engage even when the car is hot.
I'm thinking, the ecu reads postcat voltage and engages the sap to raise exhaust temps when the car is cold. If it's engaging when the motor is definitely hot then the postcat temp/voltage must be reading incorrectly. Hence the previous malfunction codes.
Agree or disagree?

What I really wanna do is change the maf, postcat sensors, both combination valves, and redo all the vacuum lines.

 

Ignition coil for cylinder 3, or that spark plug may need repacing.
Try swapping the coil with another, to see if the fault moves.