SPN 3050, FMI 11 - Catalyst Inactive on Gasoline (Bank1)

Greetings SUPRA Gurus,

Helping out a lady friend who has a 2011 Launch 22V ... Indmar Assault MPI 325 engine.

I am still running a 2004 tournament boat so do not have to worry about the problem she is having ...

She is receiving the following WARNING code, all related to the Catalytic Converter / HEGO sensor ...
Attachment 19742

Determined the following from the Indmar Engine Manual ...

SPN 3050, FMI 11 - Catalyst Inactive on Gasoline (Bank1)
FMI 11 – Root cause unknown
OC 11 – has occurred 11x
DTC 0420: Bank 1 Cat Inactive

Best I can tell from research is ... a bad HEGO sensor OR a bad CAT, obviously the former is alot less expensive than the latter.

Planning to swap Bank1 sensor with Bank2 to see if the problem follows the sensor ... that way will know if its a sensor problem or CAT problem.

Have not looked at engine directly yet so asking a Dumb Question ... is this the CAT sensor or the POST-CAT sensor? 99% sure that is "Sensor 2 - Post Cat".

Any other ideas would be greatly appreciated!

LarryG
www.ski-it-again.com

Follow-Up

Was able to get the boat out on the water this past weekend.

Boat ran rough intiially. Definitely missing. The CAT Bank1 error count went up by one and we received a bunch of misfire error codes which makes sense.

See the photo of the engine page.

Planning to get it into the shop but curious if anyone who has had the misfire codes, can elaborate on what repairs were done to fix this? Am assuming as a minimum, a tuneup will be required.
Attachment 19743

Thanks for any comments.

LarryG

Quote:

---

Originally Posted by larryg-sia

Follow-Up

Was able to get the boat out on the water this past weekend.

Boat ran rough intiially. Definitely missing. The CAT Bank1 error count went up by one and we received a bunch of misfire error codes which makes sense.

See the photo of the engine page.

Planning to get it into the shop but curious if anyone who has had the misfire codes, can elaborate on what repairs were done to fix this? Am assuming as a minimum, a tuneup will be required.
Attachment 19743

Thanks for any comments.

LarryG

---

Most CAT codes I see are an indication it needs to be replaced.

Interesting question, if the boat is a 2011, when was the last time a tune-up was done? Easy to do, parts are easy to find, and it does not cost that much if you do it yourself. Not trying to imply that will fix any CAT or Sensor issue.

Quote:

---

Originally Posted by MJHKnox

Most CAT codes I see are an indication it needs to be replaced.

Interesting question, if the boat is a 2011, when was the last time a tune-up was done? Easy to do, parts are easy to find, and it does not cost that much if you do it yourself. Not trying to imply that will fix any CAT or Sensor issue.

---

MJHKnox ... Thanks for your input.

For starters, boat was winterized by a different experienced boat owner. Obviously mistakes happen but I did not see anything out of ordinary when started on trailer before heading to the ramp for first time two weeks ago. Engine discharged the RV anti-freeze. No water spewing out of the engine as far as I could see. No odd muffler sounds, no mouse house remains coming out the pipe, etc.

Finally got the boat to the service shop. Still determining root causes but they found some free water in all LHS cylinders and the plugs had some rust on them (not sure if light or heavy). Stated the distributor cap was clean inside and wires in good shape so appears a tune-up was done prior to my friend buying the boat. Assuming RHS cylinder/plugs were fine.

Obviously water gets into the cylinder one of two ways ... a cracked block or exhaust manifold/riser. If a cracked block, less likely all cylinders on the subject side would have moisture in them, usually only one or two. Therefore, that would indicate the manifold/riser.

Upon removing the exhaust manifold/riser, tech noticed the CAT element is GONE, nothing left and the O2 sensor had moisture on it. Pressure tested the manifold and it held which is perplexing. Not sure if the pressure test was the complete assembly or just one jacket. Obviously testing the whole thing would not find an internal jacket crack. Am simply amazed the boat has never gone into LIMP MODE according to the owner, and did not while I was test driving for 25min.

At this point, until the shop finds something else, must assume the manifold/riser is the problem for both water and CAT. Not a cheap part and then there is the supply chain issue. Amazing the industry has not come up with a replaceable CAT element so you do not have to buy a whole manifold/riser casting (if the casting is ok). Then again, maybe statistically not a high failure item so they don't separate that out.

Anyone know the exact parameters resulting in LIMP MODE? On a CAT engine, usually oil press, water temp, O2 sensor, etc.

More to follow ... Thanks for reading.

LarryG