What engine?
224 code is often 2.3l engine issue
172 means computer has reach a preset limit of adding more fuel to the mix but O2 sensor is still reporting lean exhaust(too much oxygen).
This can be from a vacuum leak, but would expect high idle with that.
An exhaust manifold leak pulls in air which will throw off O2 readings
It could be the O2 sensor itself but if it is the exhaust should be blowing a bit of smoke because of rich mix.
If engine is warmed up and idling, unplug the IAC Valve, engine idle should drop even lower, around 500rpm or even stall, that would mean computer was setting the low idle for some reason.
Target idle for warm engine is 700 for manual trans, 800 for automatic