DF90 2-2 Fault or limescale buildup

[mattyk]

Hi Everyone,
We've got a DF90 that solely runs in freshwater. She's recently been suffering with bouts of overheating which we discovered was due to a huge buildup of limescale. The thermostat and pressure switch were both solid with buildup.
New stat, impeller and pressure valve later, we've flushed the engine with a marine limescale remover and she idles perfectly, strong telltale and no overheating warnings. The problem occurs when the revs reach close to 2000rpm whether that be in gear or using the throttle lever. We get what I believe is the 2-2 warning, we get 2 flashes of the engine management light then a gap and repeat.
I've checked the continuity of the CTP switch and that seems to be functioning correctly with no continuity when the throttle is open and continuity when in neutral or no revs.
Does anyone have any other suggestions of where to look?
We've taken it to a Suzuki repair centre who did the initial works but it's still failing and they're now talking about stripping the head so it's going to get expensive.
Thanks for any sugestions.

[Pbodsw]

2-2 code is an air intake instrumentation fault. Can't think why removing the head might help? Maybe related to the IAC valve and there's also a reset procedure to try?

[Moonlighter]

Check inside the cowl intake duct for obstructions. You may need to pull it apart.

You would be by no means the first person to find that a small bird or mice thought that was a good place to build a nest and thereby clog up the air intake.

Does it sound implausible? Sure! But its been reported several times on this forum and the symptoms are similar to what you are experiencing.

[catacom225]

2-2 fault would be CTP sensor i think? check screen as suggested and test

[slayray]

How do you know its overheating? If youre getting a 2-2 fault that is CTP switch and wouldnt be overheating. Are these 2 separate problems youre talking about?

[mattyk]

Hi Everyone, thanks for your suggestions. I had the intake apart over the weekend and it's free and clear. I hadn't thought about mice etc and where it's moored, that's more than possible.
CTP Switch continuity is ok, when the engine is on throttle or not so I don't think it's that either.
I jumped to the conclusion it's overheating because once it's throwing an error, if I leave it at a couple of thousand revs, I get steam coming out of the exhaust but I guess that could be something more sinister? There's no temperature light on though, just the engine management light that's flashing. Its sequence is flash--flash----flash--flash----flash--flash which I took as a 2-2 looking at the manual.
I've relented and sent it back to the repair centre so will see what they say. Will update when I hear from them for future reference.
Thanks everyone for your help.