Check Engine Liight

[jerrygeisenheimer]

I have a 2010 Yanmar 6BY engine that flashes check engine light indicating low oil pressure whenever I throttle down to 4MPH from a high RPM. The oil pressure is OK and after I stop and restaart engine all is OK. The error code is not accurate and is not indicating an actual low pressure situation. Any ideas?

 

[BB marine]

There are two oil pressure sending units. (1) is a resistor type that the gauge is connected to. The other is a switch that alarms when pressure is low. The pressure switch may be weak and alarming. Normal running conditions after a high rpm run the engine oil temperature increases and the oil "thins" from the heat. The operating pressure is ok as the engine rpm is high because the pump speed is increased. When the engine is brought down to a low rpm the oil pressure lowers. If the oil is hot (which it is) it is thin and the oil pressure is affected by this. It will show low 30 psi to 20 psi sometimes lower based on oil age and break down. After idling for a few minutes the oil is cooled ( oil cooler) and the pressure starts to increase. I am more apt to believe the oil pressure alarm over the oil pressure gauge. That said don't jump to conclusion of low pressure. Replace the sensor first then recheck. What is your oil pressure reading when the alarm is sounding or code?

 

[jerrygeisenheimer]

I did replace the oil sending unit that screws into the engine block . I also change the type of oil used swirching back to Yanmar brand. Neither made any difference. I tend to think replacing the sender alarm gauge as a possible culprit. Where is it located and do you know part number?

 

[jerrygeisenheimer]

I might add the oil pressure never drops below 20psi and usually runs higher as the rpm increases