My 1999 toyota camry just leak water and now will not start.

1999 Toyota Camry Electrical Wiring Diagram Manual Download

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Heater matrix problem

no
the problem is in the fuel pressure regulator(pressure too high)
injectors leaking, injector seals leaking
or voltage to the ECM is too low

It does sound very much like your starter. Best way to clean corosion on the battery terminals is hot water. Poor it over the terminal, no need to disconnect just watch where it is leaking as it can stain driveways.

the most common place for a leak, especially when the engine running, is the rocker cover gasket on the top of the engine. other places include the crankshaft and camshaft oil seals, the sump gasket, and as you have already said, the oil filter and sump plug.
it is a lot easier to spot a leak if you pressure clean the engine first.
that way it is much easier to see any fresh oil and where it is coming from

If the water pump have ben leaking for a while the timing belt jump timing.
what you need to do is replace the timing belt and the water pump, is about 500 dlls job.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/flavio_517b938f50183b92

under car there a small plugs to drain water from it in case there is a spillage make sure plugs are in place

The OEM SKU is REPT313504

P-0172 indicates a "too rich" condition. Thi is measured by the Mass air flow sensor. You could have a host of issues, but the MAF is first., After that, it could be leakiy injectors, vacuum leaks in the intake, exhaust leaks, etc. Have the MAF cleaned and checked first.

Replace the half round rubber gromets at the cylinder head ends just under the gasket you replaced