I replaced the air filter on my 2009 HHR 2.2 and after installing I got them error codes. They stay permanent and after clearing the code, it pops right back up. I don't understand because everything was fine before the replacement...

 

What are the codes?
Did you reconnect the MAF sensor?

 

You forgot to reconnect the MAF sensor like everybody. Or the wires are damaged, or just not clicked in.

 

P0107 MAP Sensor, Low Voltage

Yes I have connected the MAF sensor (The one connected to the engine cover) and checked multiple times. I even unplugged the sensor while it was running and the hhr immediately shuts down.

 

Would the wires still be damaged if the MAF sensor is still working?

 

It is not working. That's why the CEL and code.

Did you touch the MAF or drop it?

It should not stall if you disconnect it, maybe wires are frayed and touching?

Check fuse #33 underhood fuse box.

 

Fuse 33 is intact. If its the MAF sensor, code P0102 should pop up right? I have code P0107 which is for the actual MAP sensor.

 

You are correct! I was thinking too fast.

I suspect something is shorting the 5V ref wire.

This link has testing procedures: https://www.obd-codes.com/p0107

Check the MAF connector.

Check the wire bundle at the EVAP purge valve.

 

Is it ok to just buy one of them cheap multimeters from walmart, and how can I go about checking the vacuum without a vacuum pump?

 

I would do the wiggle test. You will need a digitalVOM, most are now, Harbor Freight sells them for less than $10.