I have replaced numerous sensors (to include the IAC) on my 496 HO in an attempt to solve my 2 beeps per minute issue. I also encounted a new alarm this weekend....cruising at 4K RPMs I push the throttle down hard to WOT @ 5K) and get a steady hard alarm. Slow down, bring the boat off plane and the alarm stops. Water temp.165, Oil Pressure 40, 12+ volts and the seawater impellar was replaced earlier this summer. Bring the boat back up on plane and ease the throttle to 5K - no alarm (except 2 beeps per minute). Any thoughts? BTW...its time for a Rinda Scanner. I'm not a mechanic, but I'm going to order one today. From what I've read on this forum the RINDA seems to be the most popular scan tool. Thanks, Don

Water pressure is 165? If that's not a typo, that is a problem.

yes, typo....water temp 165. Don

What is the water pressure?

When I purchased the boat it did not have a water pressure gauge, only water temp, oil pressure, volts, speedo, tach. I guess they thought the guardian would take care of the monitoring.

Your alarm is probably the low water presure sender on the raw water pump housing. If it is infact the low water pressure alarm One of three things come to mind.. 1. You have a failing or impeller and water pressure is low. 2 The impeller housing is scored , thus not creating the needed water pressure Both 1 & 2 will cause a hard alarm at high RPM. 3. The sensor is bad or has debris in it. I went round and round with my raw water pump on my 496, replace impeller, and housing only to have it alarm again. I then replaced the sensor and all was good. Took a closer look at the old sensor and it had sand cloging the hole..... Remember the 496 has closed cooling, so the temp reading you are getting is of the Anti-Freeze/Coolant in the motor. It is very possible to have enough water to keep the exchanger cool, while still being just below the psi requirement, thus triggerng the alarm. Or the sensor could be pluged or going bad. FYI, If you unplug the sensor, you will get the 2 beeps every few minutes.

I received my Rinda Scan Tool last night. The following faults were displayed:

Freeze Frame Memory
Pitot CKT Lo Code is active 94
Fuel level CKT Hi Code is active 75
Steering CKT Hi Code is active 118
Fuel Level 2 CKT hi Code is active 191

In the fault history the following code was displayed:
Oil Pressure CKT HI 84

In the Read Fault Secs the only item with any seconds was Guardian (362 seconds) and Overspeed (62 seconds)

Also displayed available power 100%

I guess I need to purchase a diagnostic manual for the PCM-555. I believe most of these faults are active all the time and are not used. At this point not sure if any relate to the 2 beeps per minute or the steady tone when running hard. I assumed that I would see a few more faults. Any thoughts.....

Clear all the faults and run the boat again and see what you get.

yep, I was headed to the lake today and the storms hit....I'm 5 minutes from the boat ramp, maybe I can get out this evening. Thanks!

Ran the boat this evening and here are the readings from the scan tool with FF data:

Fault 84 Oil PSI CHK HI
RPM 754
Fault Freq count 3
Main PWR Relay yes
Fuel Per Cycle 27.3 MG
Engine Load 9.8%
Available PWR 100%
Battery Volts 14
Block Pressure 1.6%
Demand 2.9%
Throttle PCT 2.9%
Manifold Air Temp 116 degrees
Barometric Pressure 14.3 PSI
Manifold Pressure 9.6 PSI
Coolant 158 degrees

Guardian Fault #9

RPM 4922
Fault Freq count 0
Main PWR Relay yes
Fuel Per Cycle 73.5 MG
Engine Load 33.8%
Available PWR 89%
Battery Volts 13.2
Block Pressure 9.4
Demand 73.1%
Throttle PCT 73.1%
Manifold Air Temp 104 degrees
Barometric Pressure 14.3 PSI
Manifold Pressure 12.9 PSI
Coolant 167 degrees

Exhaust manifold temps: Port 137, Stbd 128

any thoughts? Having the scan tool was great!