Ignition Light Insufficient Oil Pressure

Hello, I have a 306 TD with 18 years and the other day I came up with the great idea of ​​oil the engine a little because once I made this the next day when everything was normal, the oil pressure light was turned on, the stop and the temperature of the water stops and everything was normal when it turned it on again everything was normal but every 30 or 40 kilometers it again, a friend told me that it was from the sensor of the pressure of the oil. being the car has the perfect levels and the temperature of the water does not supply

Something similar happens to me in the Peugeot Pertner, the same light and the stop, but oil and water temperature levels are ok and I do not know what it can be ... I have worried that theme ..

In the case of Nikolass it seems that the issue was when cleaning the engine, I would advise you first

And state checking the relays and there is no apparent problem but now it goes and if the battery fucks but we are not going that that was the problem at the moment has not done it to do thanks ...

In the first case Czech the connectors of the cable