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Help! O2 Sensor Code Diagnostics


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Gents! This last Saturday I had a whole host of problems...first I felt a slight pause when I pushed the throttle to get on plane and then the boat temp started to roll up above normal (160F thermostat). Later I found a metallic noise like bad bearings on the belt drive. Limped back to the dock and went straight to the shop to pick up a new seawater pump because that is were the metallic rattling noise seemed to be coming from. One new seawater pump installed later and the noise was still there. Went out on the lake to test'er and a 30 min boat ride later same problem with the noise and temperature wanting to roll up about 180F when attempting to get on plane. Decided to cruise back to the boat lift late at night and had a lot! read a lot! of water in the bilge...auto bilge decided not to work and my center bilge failed too. Needless to say it was getting deep and submerging the lower part of the v-belt drive. I got low voltage (alternator was not working due to the water partially submerging it) and luckily the rear bilge worked to get the water out just in time and the alternator started charging the battery again. After that the boat threw 3 codes for O2 sensors (water splashed on O2 Sensor?). Needless to say it was a hellacious night and there was an instance where I contemplated if we would sink...luckily we didn't!


SPN 66019 FMI 8

SPN 66020 FMI 8

SPN 627 FMI 17

Can someone help me locate the O2 sensor with the issue!? Is it port or starboard? before the CAT or on the stainless dump. I'm trying to do the diagnosis without the scan tool...as they are quite expensive. Thanks!

2014 Axis T22, Indmar Monsoon 350 W/half closed cooling system. Exhaust manifolds are raw water cooled.

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  • 2 weeks later...
On 6/19/2018 at 5:27 PM, ILikeToParty said:

W/half closed cooling system. Exhaust manifolds are raw water cooled.

I'd like to know more about this part - half closed cooling system? I also have a '14 T22, but with a different issue (ignition)

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SPN 66019 FMI 8, oxygen sensor bank A sensor 1 heater abnormal frequency or pulse width .  That is the cylinder 1,3,5,7 bank, or starboard on a vdrive, pre-cat sensor in the manifold.

SPN 66020 FMI 8, oxygen sensor bank B sensor 1 heater abnormal frequency or pulse width .  That is the cylinder 2,4,6,8 bank, or port on a vdrive, pre-cat sensor in the manifold.

SPN 627 FMI 17, system voltage data valid but below normal range.

Check the harness plugs on the O2 sensors for moisture or corrosion.  Try swapping them with the post cat sensors and see if you get the codes again.

Take the belt off the motor then run the motor for a minute to see if the noise is still there.  Turn the idler pulley, alternator, circ pump by hand to see if they are loose, worn or corroded.

The water leak sounds like the biggest issue.  If it is from the seawater cooling system, that could cause the motor to run hot.  See if the transmission cooler or heat exchanger is clogged or if the thru hull inlet valve isn't all the way open and check the coolant level. 

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