I am throwing code 34. I have been since I took off MAF screens a while back , but the other day check engine light flashed and car idled rough, died, wouldn't start. Went back later and it started right up. Checked codes and got the familiar 34 and then got 46. What is it?

 

Code 46 is for the VATS System.

I don't know how to do it, since mine hasn't done this but you can check the resistance on the chip(little black square thing) in your key. I don't know what the resistance should be, maybe someone on here knows. Do a search for VATS issues, I've seen it on here many of times.

Code 34 = MAF Sensor

Put your screens back on and see if the Code 34 returns, if so
follow the below instructions.

When the ECM see's low air flow less than 2.5 gm/sec ie.(Low Voltage) for 1 second you will get the code 34.

1) Check for loose or Damaged Air Duck, If so repair it.
2)Ignition "OFF" clear codes, Diagnostic terminal NOT grounded,
Start engine and run above 2000 RPM's until "Service Engine
Light" comes on, Ignition "ON" engine stopped, Ground
diagnostic and see if code 34 returns.
3) No code 34, Problem is intermittent
4) Code 34 retuns, Ignition "OFF" clear codes, diagnostic terminal
"NOT" grounded, disconnect MAF sensor, start engine and run
above 2000 RPM's until "Service Engine Light" comes on,
Ignition "ON" engine stopped, Ground diagnostic terminal and
note code.
5) Code 33 shows up, it's a faulty MAF sensor
6) Code 34 returns, check for short to ground in Ckt. 998, If not
shorted to ground, it's a faulty ECM.

Ckt. 998 is connected to your MAF at Pin "C" and that is
connected to your ECM on B12 (whice is your MAFs current
limiting 5v signal from the ECM).

For a quick check, disconnect your MAF sensor and start your car, If the Idle improved then replace your MAF sensor.
This test will determine if the condition still exists to set a code or if the problem is intermittent.
With the MAF sensor disconnected, the ECM should see a high voltage (High air flow) near 5v and set a Code 33. If a Code 34 resets then the wiring or the ECM is at fault.

Let me know what you find out.