Throwing 4 codes

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Finally got around to checking the codes in my wife's 1994 Turbo wagon.
The following codes are being thrown and making the car nearly impossible to drive.
22 - Knock Sensor
32 - Oxygen Sensor
35 - Canister Purge Valve
49 - Use of improper air flow sensor

The car is in decent shape and I have all of the records pertaining to previous work done. The knock sensor was replaced at the dealership 2 years ago along with the timing belt.
The only modifications I've made to the car.
-Copper core NGKs
-New wire set
-New fuel filter
-New air filter
-90* silicone reducer to replace cracked and broken snorkel on intake
-New CTS

There is also an aftermarket alarm installed that doesn't work. What are the odds all of the sensors listed are faulty? Or is there a bigger issue somewhere else?
Thanks guys, any help is appreciated.

[Legacy777]

I would suggest resetting the ECU and see what codes come back. I doubt all those are current codes. In addition, you can run the active diagnostic using the green connectors and the procedure on my site. www.surrealmirage.com/subaru/engine.html

This should tell you what active codes there are. I'd start with that before troubleshooting any more.

Just curious, are you running the Aluminum body MAF?

[-B-]

Great I will. Yes, aluminum body Hitachi.

[Legacy777]

Ok, yeah clear the codes, see what comes back, and perform the active diagnostic.

[-B-]

Just did the active diagnostic. The only code being thrown is a 51, doesn't make much sense since it's an auto.
I must be reading it wrong, I'm going to reset the ECU and try again.

[-B-]

After resetting the ECU did the active diagnostic again. Code 51 is what I'm coming up with.
Just in case I attached a video.
View My Video
The rattling is something in the back not the engine.

[Legacy777]

Code 51 is also the inhibitor switch in the automatics. I don't know if that code would cause the engine/car to be undrivable. You can d/l the factory manual from me and run through the troubleshooting procedure for code 51.

http://www.main.experiencetherave.com/s ... _and_Elect

[-B-]

The previous codes are stored on the ECU again. This is driving me nuts, I'm going to have her leave it with me this weekend and see if I can't track the issue down. With DSMs multiple codes will often times mean a burn on an ECU trace or another issue related to the ECU, is this a problem in the scoobs?

[Legacy777]

I have found from past history of other people that these ECU's will sometimes not clear if the canister purge solenoid code (35) is active. My hunch is because this is an emissions related item.

Also, I have found that sometimes the ECU's won't clear using the battery method and you need to use the procedure of connecting both the green & black connectors while following the procedure on my site. One of the members had this issue and it may be related to whether the car is designated a "federal" or "california" car.

I'd suggest trying method to clear the ECU by connecting both the read & active memory connectors.

[-B-]

Swapped the maf and fixed the broken intake tube. The other codes are gone after clearing them.