Mercruiser inboard 4.3 mpi is giving a constant alarm

Hi

Hoping to get some help fixing my Mercruiser 4.3 MPI Serial: 0W031854

When I start the motor and it has run for 20-30 seconds I get a constant alarm sound.

I have checked Oil and Stern drive levels and they are OK
I have tried to disconnect the Temperature and Sterndrive sensor with no success

If I disconnect the Oil pressure sensor the constant alarm is replaced by a 2 beep alarm instead.
I can see that the sensor is rusty.
My guess is that the 2 beep is because the sensor is disconnected ? , when I plug it back in and start the engine the constant alarm is back.

If I look up my engine at https://webapps.brunswick.com/literature/literatureSearch.do
I can find under "Instrumentation-Gauges and Components"
Gauge and mounting hardware, Oil pressure
what I would have supposed was the sensor, but this looks nothing like the one I got on the engine.

Could somebody help me find the right part for my engine ?

Re: Mercruiser inboard 4.3 mpi is giving a constant alarm

Hi there, unfortunately on MPI engines there are many things that will sound off the warning horn. The only way to know for sure is to scan the engines pcm/ecm to see what is going on, usually anything else is just a expensive guess.

Also please keep in mind unplugging sensors with the key on will actually make it a little harder to diagnose due to you are creating another fault that will show up on the scan tool that may get treated as the problem with full diagnosing potential if someone else at a service shop for example did not remember you telling them you unplugged certain sensors.

It appears the sensor you're looking for is merc part number 881879A6 SENSOR, (0 - 100 PSI), Oil Pressure

You can find this sensor inside the parts catalog section under cylinder block, cam, crank, balance shaft, or this and more sensors under electrical components of your link.

WARNING HORN SIGNALS
Most faults will cause the warning horn circuit to activate. How the warning horn activates
depends on how serious the problem is. There are five warning horn states:
? None. The horn is silent
? Caution. The horn signal varies with product line and calibration. Minimal guardian.
? Warning. The horn signal varies with product line and calibration.
? Severe. The horn beeps constantly.
? Critical. The horn beeps constantly and guardian will be at forced idle.

Good luck.