Look for the switch on the oil filter base.
Part# 239 (which supposedly in only found on TYPE 0435.

Likely, if you simply disconnect the wire, you can prove/disprove your theory.
The parts manual says it's normally closed. That would ground the kill wire to the coil.
Pressure should open it, allowing spark. Disconnecting the wire should do the same.

In the states, it's rare that garden tractors etc. have a low oil pressure switch. I guess they're afraid the engine might die when crossing a highway?

Most of the time when there is an oil related switch involved in no spark situations, it is a LOW OIL LEVEL switch or sensor, not an oil PRESSURE switch.
Generally, an oil pressure switch operates to control an oil warning light on the meter panel.
When a low oil level switch/system is involved, as Bill says, the sensor grounds the magneto and keeps it from making a spark. And, as Bill stated, disconnecting the wire from the low oil sensor will allow the engine to start.
There are low oil pressure set ups that will stop an engine if the oil pressure drops, but those systems require either a manual over rule switch, or a momentary timer...... to allow the engine to start up initially as there is no oil pressure until the engine runs. It would seem to me that if it was using a low oil PRESSURE system, and a start up timer was part of the circuitry..........the complaint you would be reporting would be that the engine starts up but only runs a couple of seconds before dying. and it would repeat that as often as you tried to start it.
But, if the trouble is due to a low oil LEVEL system, that kind of system should do just like you describe.....if the oil sensor is higher than the oil level, and if the engine is not really "low of oil" when it is preventing the engine from getting spark, I would have to say that is "Chinese engineering at its very finest moment.
So, I am not sure whether your machine has a low oil level switch or a low oil pressure switch.
In cases where I have seen low oil level sensors on Briggs engines, they are usually placed into an unused oil level check plug on the crankcase.

Mownie-
The IPL for a 445577 does show a switch.
Part# 792028

Since the poster is in OZ, things are probably a bit different there.

This post was edited by bill_kapaun on Mon, Mar 24, 14 at 10:09

Yes Bill, I saw that it has an oil PRESSURE switch.
But, as you stated, here in the US of A we don't usually see shutdown systems tied to the oil pressure. Having a shutdown system that kills the engine upon a drop in oil pressure requires that a provision be made that will permit the engine to make a spark in the ABSENCE of oil pressure in order to allow the engine to be cranked up from a dead state.
Provisions for this can be a manual over rule switch that the operator must enable during cranking, or more sophisticated systems can feature an automatic electronic timer that will permit the spark to be present for about a 10 second period before arming the shutdown circuit.
Once the shutdown system has been armed by either method, any loss of oil pressure will have the shutdown work and kill the engine.
If.....this Ozzie configured machine has an oil pressure shutdown system, it MUST also have some kind of provision to allow spark during cranking when there is no oil pressure at first.
Now, on the shutdown systems I am familiar with, there is a 10 second timer which allows spark in the absence of oil pressure to assure engine starting. After 10 seconds of time (beginning when the key is turned on) without an oil pressure signal to the shutdown module, the engine will be deprived of spark. On those systems, if you simply turn the key on and let it remain on for more than 10 seconds before cranking the engine.............you will never get the engine started because the timer has run down and enabled the shutdown module.
In lieu of a bona fide wiring diagram by the machine OEM (not Briggs) anybody trying to diagnose this is fielding their best SWAG technique.
I am just hoping to provide some food for thought on the subject in general, not knowing any specifics of circuitry on the machine to go by.

Mownie- I'd also thought about the no oil pressure start up problem. Possibly it's simply a matter of keep cranking until it builds enough pressure? I have no idea how long that would take, especially after doing an oil & filter change???

Having a schematic would be so useful. Even more useful than knowing what this engine is "attached" to!

We have him on another forum, he does not have a oil switch. The ipl shows a switch, but in the reference-part number list, that reference number does not show a part
number, meaning his engine doesn't have the switch.

Sorry for not closing this - it was a loose wire not properly crimped