PUTS OUT CLOUDS OFSMOKE AFTER IT WARMSUP AND LOOSES OIL

Try MTD Parts or Jack's Small Engines.

https://www.google.com/search?q=YBSXS+2051+hp+tiller+replacement+belt

..

The YBSXS is a family number. You need to locate the model number for the parts list. See the Briggs website.

https://www.briggsandstratton.com/na/en_us/support/need-help.html

If the diaphragm was busted and with that amount of oil lost I would be seeing oil tracks along the vehicle and under the floor pan. Also there would be a red light on for the oil pressure as the diaphragm has a spring behind it which closes the electrical points and allows the oil light to go off when pressure is above the low oil pressure setting. It may be but I would be looking else where for the problem. I would be looking at valve stem seals broken. These allow the oil to be drawn down into the cylinders when idling at lights and will come out as a puff ofsmoke when taking off and only lasts a few seconds

when the CPU puts the engine into limp mode it is telling you that something very serious is about to happen to the engine or transmission and if you wish to ignore it by trying to circumvent it by fiddling with the ignition then you will be paying out big dollars soon. The idea is that as soon as it goes into limp mode for what ever reason you stop and check the oil and coolant levels and then have the fault codes read as soon as possible so that extensive damage can be prevented.

check your turbo is ok

have you checked the oil level? Any lack of power when light comes on? Any smoke?

In some cases worn cam bearings can cause it. Not saying I know that applies to your vehicles engine. Just an unpleasant thought I had.

How low does the pressure get? It only takes 4 psi to keep an engine lubricated. The pressure will drop off as the engine get to operating temperature. This is normal. As long as the pressure climbs instantly when you accelerate you're ok.

try the coil. the coil will produce the spark for the spark plug seeing as there is no battery, try replacing it with another of the same power.