Help with diagnostic code reading

[sfjakey]

Hoping someone can help decipher this. When I run my boat, 2015 230 with the zr409, I get this code which comes up regularly. I dismiss it and keep running, but it is irritating and I would like to permanently mute it. My understanding is it is a sensor that is bad, but not impacting performance. What sensor specifically? And any way to just bypass this emission stuff?
picture attached. Code says DTC 160 EG 04 open/lazy. SPN 3266 FMI 5
thank you

[jpwhit]

The error indicates that the ECU thinks the Catalytic Converter(s) is not functioning properly. It determines that be comparing the two Oxygen sensor readings for the sensors before and after the Catalytic converter. And yes, often the issues is caused by worn out oxygen sensors. Knowing the hours on the engine would be helpful, and hours since oxygen sensor have ever been replaced already. Oxygen sensor are consumables like spark plugs, they have a fairly well defined lifetime.

But, it's not always the case that this is purely an "emissions" error and it's fine to ignore. Because it can be the O2 sensor before the Catalytic converter failing and that sensor is also used to control the fuel mixture. And if that sensor is failing, then the boat will tend to run rich, which ironically can burn up the Catalytic Converter. And those Catalytic Converters are darn expensive. When I get these codes on a boat, I replace all 4 oxygen sensors. Then if the error comes back, then the Catalytic converter is likely bad.

I don't know of any way to disable these checks w/o causing other issues.

[Scooter G]

Looks like an Exhaust Sensor issue on Bank 2 Sensor 4
Follow the Diagnostic Manual searching 3266 or SPN - 3266

PCM Diagnostic Service Manual.pdf

[sfjakey]

Looks like an Exhaust Sensor issue on Bank 2 Sensor 4
Follow the Diagnostic Manual searching 3266 or SPN - 3266

[ATTACH]n678398[/ATTACH]

is bank 2 port or starboard? I assume sensor 4 is post cat. Engine has about 430 hours.

[sfjakey]

The error indicates that the ECU thinks the Catalytic Converter(s) is not functioning properly. It determines that be comparing the two Oxygen sensor readings for the sensors before and after the Catalytic converter. And yes, often the issues is caused by worn out oxygen sensors. Knowing the hours on the engine would be helpful, and hours since oxygen sensor have ever been replaced already. Oxygen sensor are consumables like spark plugs, they have a fairly well defined lifetime.

But, it's not always the case that this is purely an "emissions" error and it's fine to ignore. Because it can be the O2 sensor before the Catalytic converter failing and that sensor is also used to control the fuel mixture. And if that sensor is failing, then the boat will tend to run rich, which ironically can burn up the Catalytic Converter. And those Catalytic Converters are darn expensive. When I get these codes on a boat, I replace all 4 oxygen sensors. Then if the error comes back, then the Catalytic converter is likely bad.

I don't know of any way to disable these checks w/o causing other issues.

I would think the cat could be deleted if bad? Bypass these sensors, let it run free

[jpwhit]

I would think the cat could be deleted if bad? Bypass these sensors, let it run free

Possibly, bypassing the sensors would be the tricky part. The O2 sensors generate a series of pulses that the ECM interprets. If you just unplug them I think you'll get a constant stream of error codes. They make "fake sensors" for this purpose for cars, but I doubt those will work on a Marine engine because the operating environment is so different. I've never seen the same thing made for Marine engines.

[Scooter G]

I haven't had to replace my sensors yet, but assuming 2nd sensor from front to rear, port side.
Banks run according to #1 plug firing order, plug 1 is the1st plug towards the front on the starboard side (bank 1).
JP may know, I would hope it is after-cat because there is a big mood swing on prices. Out of my league at this juncture, here to get you close, real real close.

Nautique Parts has a pretty good schematic for reference:
https://nautiqueparts.com/ces-exhaust-5-7l/

Edit: Sorry that's for the 5.7, but not far off

[Scooter G]

What was the outcome here sfjakey?

[schaNYC]

I'm having similar issue on my 2014, different DTC number. Had an O2 sensor replaced by dealer after diagnostics but still getting the warning. Perhaps I need to replace others. Much like the OP, I hide msg and carry on. Have not noticed any ill effects so far but will have dealer take another look after the summer season.

[sfjakey]

What was the outcome here sfjakey?

I have not had a chance to replace the sensor and run the boat yet. It’s sitting 9n the workbench waiting for some free time. Hopeful and I will update after

[sfjakey]

I haven't had to replace my sensors yet, but assuming 2nd sensor from front to rear, port side.
Banks run according to #1 plug firing order, plug 1 is the1st plug towards the front on the starboard side (bank 1).
JP may know, I would hope it is after-cat because there is a big mood swing on prices. Out of my league at this juncture, here to get you close, real real close.

Nautique Parts has a pretty good schematic for reference:
https://nautiqueparts.com/ces-exhaust-5-7l/

Edit: Sorry that's for the 5.7, but not far off

So I just looked at this. When we refer to port and starboard, that is in relation to the bow of the boat, technically speaking. I assume in this case, that is reversed since the engine is mounted rearward facing? In this case port and starboard are reversed?

[Scooter G]

I think I get what you are saying. Regardless of which way the engine is facing, port is port (left side), starboard is starboard (right, driver's side). But in this case port would be the right side of the engine block per se.
Even if the engine is upside down port is on the left in reference to the boat, not engine, lol.

[sfjakey]

Port and starboard refer to the boat itself. The engine is mounted rearward facing, so port on a vdrive engine is actually starboard on a direct drive. The engines are the same, just mounted opposite. So which side refers to “port”?

[Scooter G]

You are way over thinking this. Port is always left when facing the bow of the ship in reference to anything on it or in it. Your reasoning is correct if it read "on the left side" of the engine.

Who's on 1st..?
~Abbott & Castello

[sfjakey]

I know port and starboard. PCM uses the engine in many applications, therefore port and starboard are irrelevant. Is bank 2 on the left or right of the engine looking at it from the front?