I doubt you will hurt the engine but it could leave you stranded, and maybe with a towing bill.
172/176 are Lean codes, so running rich would be the opposite, UNLESS, the Lean codes are both O2 sensors being bad, very very long shot for both to fail at the same time, OR the computer or wire reading the O2 sensors is bad.
O2 sensors are the final says on air/fuel mix.
They generate their own voltage, .1 to .9volts, .1v is Lean, .9v is Rich
lean means too much oxygen in exhaust
rich means too little oxygen in exhaust
So O2 sensor can't see fuel just "O"xygen, if it could see fuel it would be called an HC sensor, lol.
Computer opens fuel injectors for a specific time based on MAF(air flow) sensor data.
After fuel is added it looks at O2 sensor voltage, if voltage is .2(lean) then computer opens fuel injectors a little longer, then looks at O2 voltage again, if it is .7(rich) it closes injectors sooner.
Computer changes injector open times at least 10 times every second, and O2 voltage is read at least 10 times a second.
So system is very fast at adjusting air/fuel mix to get best O2 voltage, .35v to .45v, is the sweet spot.
If an O2 sensor should fail Lean and show .2v when it should have .4v then computer would be adding more fuel than needed so engine would run rich and computer would think everything is fine.
Or if the connector at the computer or O2 sensor had moisture inside it, then the correct .4v from O2 sensor could end up as .2v at the computer because of the corrosion.
Fuel mix does have a "sanity check", if above should happen the computer would be opening fuel injectors Longer to add the extra fuel to bring up voltage on the O2s, Computer has baseline of how long fuel injectors should be open based on MAF data.
If computer is opening them too long then computer will set Lean code, engine is never running Lean, lean codes means computer thinks it is adding too much fuel for the MAF datas air flow.
Which happens with a vacuum leak, not all the air is coming in thru the MAF, so computer is having to add more fuel than it thinks it should, Lean code.
For rich running also check Fuel Pressure Regulator(FPR) on fuel rail, front passenger side, lower intake.
It will have Fuel return line and a vacuum line, remove the vacuum line and check it for fuel, if FPR leaks fuel gets sucked into engine, causing rich mix
Misfiring engine can cause lean codes as well, because O2s "see" only oxygen, if a cylinder misfires the oxygen is not burnt with the fuel, so it is dumped into the exhaust and O2 voltage goes down.