350 Mag MPI Engine key sensor fault

[silver_power]

Hello, during the last 15 days i have a problem with my water pressure sensor, which i have not change it yet. Now, I have another one fault to the smartcraft screen that sais "key engine sensor fault.restart the engine and if the fault persist,see the dealer". I noticed that this fault appears to the smartcraft only if the water pressure sensor fault appear. For example ...i was approaching the dock and two beeps was heard.the water pressure sensor and the key engine faults appeared. Then the beeps stoped. After about 5minues i unpluged the water pressure sensor and immediately the teo faults appeared,with the two beeps also. The engine runs just fine . I know that i must change the waterpressure sensor,but why the other fault appears? Do you know wht is the key engine sensor fault and what i have to change?thank you very much!

 

[Fun Times]

Re: 350 Mag MPI Engine key sensor fault

key engine sensor fault as in "ignition key" fault? or is there a symbol of a key on the display telling you there is a sensor fault of some kind?

A key engine sensor fault would most likely be incorporated in to the newer DTS system (Mercruiser digital throttle and shift).

Do you have as scan tool to clear the sensor faults?

If you don't have a DTS system or no push button ignition key or SmartStart system then this fault might be showing due to possible low 12 volt power issues have occurred at some point or in rare occasions the PCM is throwing out unusual random faults that sometimes can be cleared and sometimes not. Try clearing it and see if it comes back.

SmartStart
The system is configured to incorporate SmartStart. The SmartStart feature incorporates push button starting. Rather than holding the start button or key switch to start the engine and then releasing it when the engine starts, SmartStart completely controls the starting process. When a start request is initiated, the DTS system signals the engine PCM to start the engine, which closes the starter relay. The starter relay energizes the starter solenoid mounted on the starter motor and the engine begins to crank over.
If the engine does not start, the slave relay circuit will be opened and the cranking of the engine stopped when the time out expires. The starting time‑out is 8 seconds (3 seconds when there is no crank position sensor signal) or when the engine reaches 400 RPM. If necessary, the start strategy also adds fuel and spark advance to aid starting.
Single and multiple engine installations use the same strategy for SmartStart. Attempting to crank the engine with the engine already running will turn the engine off. Turning off the key switch will stop the engine instantly.

 

[silver_power]

Re: 350 Mag MPI Engine key sensor fault

My engine is without DTS, and it starts normally hot or cold and also never turns off without turn the key,..... so i am wondering why this fault sometimes appears. I am also trying to find out how this fault get in relation with the water pressure sensor since that when i unplug the wtaer pressure sensor, the two faults (for water pressure and the key engine sensor) simultaneusly come up.
I probably have to change the water pressure sensor, to check if everything go normal again.
Do you know if the engine runs at full power even i have the water pressure sensor alarm? The smartcraft screen does not show any message of power limitation but somewhere i read that when ther is a sensor fault (with 2beeps per minute signal alarm) the ecu limits the power to 90%. Is taht true. Can the ecu limit the power without show a message on smartcraft screen?
Thank you very much.

 

[Fun Times]

Re: 350 Mag MPI Engine key sensor fault

so i am wondering why this fault sometimes appears. I am also trying to find out how this fault get in relation with the water pressure sensor since that when i unplug the water pressure sensor, the two faults (for water pressure and the key engine sensor) simultaneusly come up.

I probably have to change the water pressure sensor, to check if everything go normal again.

Do you know if the engine runs at full power even if i have the water pressure sensor alarm? The smartcraft screen does not show any message of power limitation but somewhere i read that when ther is a sensor fault (with 2beeps per minute signal alarm) the ecu limits the power to 90%. Is that true. Can the ecu limit the power without showing a message on smartcraft screen?
Thank you very much.

Yes it's true, low water pressure will drop the available power down. I'm not 100% sure if you will always see a message on the smartcraft screen or not but i believe it's possible you may not. The scan tool shows you the available power percentage values in real time, that is what you should go by in my opinion.

It appears you probably may have to change the water pressure sensor to see if the fault/s goes away.

As far as wondering why the other "key" fault sometimes appears could be again low 12 volt power (bad ground somewhere) issues have occurred at some point or in rare occasions the PCM is throwing out unusual random faults that sometimes can be cleared and sometimes not.

 

[silver_power]

Re: 350 Mag MPI Engine key sensor fault

Thank you very much,....
so i have urgently to change the water pressure sensor and see if the faults will go away...
Thank you again.