What can happin if u drive a s430 with no coolant for a short time about 15 mins

Not nearly enough information and this is not a problem you are going to fix on a computer web site!

Have the codes read. I haven't worked on any thing to date that reduce power because of the coolant system or the oil. I have done some that will kill the engine because of both, but not reduced power. This could be from an engine hard part, sensor or wiring. Most times it's caused from a transmission problem.

After the MIL is turned off or the battery was disconnected for some time, all monitors are set to incomplete. However with several short trips with engine getting at least to hot enough for thermostat to open, (I believe 8 is the magic number of trips) most monitors are set, you may be able to pass the test with only one incomplete only.

is it fuel or spark thats what you need to check the older models have problems with relays overheating it is possible you can check the codes with the key on i think its 3 times the ignition on and keep it on the third time without starting and count the times the check engine light flashes it should start 1 long 2 short and if no codes 3 short and 3 short or 1 long 2 short so try it and check all first fuel spark whick one cuts off when wont start

bad thermostat, they are short lived parts.
replace it , and install it in the correct direction and bleed hole or jiggle pin up hill.
easy.
or the radiator is only 1/2 full of coolant,
take off the cap and see down hole, dead cold
no green ? bingo.

Is your car overheating?

That's why you do a leak test, o-rings and leaks at compressor do happin,
I hope you added freon dye, or it's going to cost you freon again, when vaccuming the system for 30 min. and static pressure for 15 min.. the static is when you turn the vac. pump off for 15 min. and there is no loss of vacumn, you have to have A/C gauges, with front and rear A/C takes 46 oz freon and 13 oz of pag 46 oil, only front A/C 34 oz freon and 9 oz pag 46 oil,

I would recommend replacing the in-line fuel filter

Most likely scenario is you could have a bad thermostat. Remove it check it and replace it if found faulty.Mike

there would be salt formation in the radiator which would turn the engine off and also may be the spark plug would be weak so try to clean the radiator and change the spark plug also.