Got 4 trouble codes for my 97 Maxima 5 speed...

1.4 Speed Sensor
3.2 Exhaust gas recirculation system flow problem
3.4 Knock sensor
7.5 Evaporative Emission Control System

My thoughts so far: Every time I have had ANY other issue, the Knock Sensor throws a code, and have seen others say similar so I think that one might be a false positive with these cars?

The car failed smog last few years, and our EGR valves seem to be a common problem, so I would not be surprised if the EGR system has a problem

Shortly before the check engine light came on, it had some trouble starting (slow crank). A day or so after I checked the codes, it won't start at all.

Honestly seems like the Starter is bad, so I planned on just replacing that. Battery and Alternator are fine. Unfortunately the area it is parked in (apartment complex garage on busy street) doesn't lead to being able to push-start very easily.
Would any of the above trouble code systems realistically cause a no start condition???

Thanks in advance for any help!

 

No... none of those codes (issues) will prevent you from actually turning the engine over. Nor would they prevent the engine from starting and continuing to run.

If you had noticed the starter seeming to become sluggish and slow AS IF the battery was running down, yet the battery is known to be good, then it's time for a new starter. If there's any doubt, however, about the battery being healthy, you should rule this out with a load test (Autozone, etc.). Replacing the starter is not a bad job. Easily done with a few basic tools. Just need to completely remove the air-box first. There are two bolts holding the starter. One 17 mm long bolt and one short 14mm bolt. For the 17mm, a long-handled ratchet driver with a flex head and maybe a 2" extension for the socket make its removal a piece of cake, otherwise it's a little tricky.

To be more specific, the EGR "System" is problematic. I'd say the EGR valve itself is pretty robust and not likely to need replacing.

Two of the most common issues (highlighted with red 1 and 2 below):
1) dried and broken rubber hose (only about 1.5" long) between the EGR valve and the BPT (Back Pressure Transducer). When this hose breaks, it's impossible for the EGR valve to open and you'll get the LOW flow code (0401).
2) partially or completely clogged manifold-to-egr tube. This is not an "IF," but "WHEN" scenario, and if you have over 100K miles and it's never been cleaned, then for sure, it's clogged to some degree. This prevents the exhaust gas from actually being drawn in to the intake manifold and therefore the temperature sensor (no. 3 in drawing below) will likely report a low value to the computer when it's supposed to be measuring hot exhaust and again trigger the low flow code.




Cleaning out the manifold tube (red #2 above) properly requires it to be removed completely. This is an egregious task to say the least and plenty of info on here about some of the tricks for getting it off.
Cheers