IAC output Error 152

Todd320 · Dec 19, 2016

I have 2007 Merc inboard with V-drives, 350 Horizon MPI, serial number OW399nnn, the port engine is showing an error code 152, IAC output error. Engine runs fine, but every 2 minutes I get an alarm. I plan on replacing it, the gasket IAC muffler, and clean the flame arrestor while I am there. If that doesn't correct it, what else could it be, or is it almost always a bad IAC?
To be safe, I returned to port on one engine, since I was only a 1/2 mile away.

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480ces · Dec 19, 2016

Start with the IAC. I've seen a few cases where a bad IAC draws so much current it burns out the control output on the ECU (poor design).

As a result, DO NOT RISK swapping IAC's. You may nuke the other ECU.

If one failed other other is on borrowed time, so do them both!

spikedaddy99 · Dec 19, 2016

IAC usually rears itself as the boat failing to hold idle. When increasing RPM's the motor will work fine. I never had an alarm when mine failed. I just replaced them both, and the filter and gaskets when 1 failed.
Mike

Todd320 · Dec 20, 2016

The boat idled just fine prior to leaving dock, the alarm went off at 3800 rpm while cruising. When I slowed down, I did not notice the engine idling bad, but I was not paying much attention.

Brown Eyed Girl - 2007 Sea Ray 320 Sundancer, 350 MAG MPI V-drive

GCHOG · Dec 20, 2016

Hi Todd, definitely sounds like the IAC. Very easy fix, about 15 minutes tops. I found a direct replacement on Amazon for about $ 40, (much cheaper than Merc). Good idea to replace the muffler +filter too while your there. Get that from Merc. I can get you the IAC part # later tonight if you want it. Its not a bad idea to keep a spare onboard since it is inexpensive and an easy fix. They don't go bad that often but very annoying when they do and can be difficult to handle the boat when they do.

Garry

Todd320 · Dec 20, 2016

I purchased everything from wholesale marine, IAC, gasket, and muffler. Bought the Sierra version of the IAC, was 85$ so not bad. The gasket did not ship, not sure why. Is the gasket metal or something else?

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bbwhitejr · Dec 20, 2016

Todd320 said:
I purchased everything from wholesale marine, IAC, gasket, and muffler. Bought the Sierra version of the IAC, was 85$ so not bad. The gasket did not ship, not sure why. Is the gasket metal or something else?

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Gasket is a fiber material like regular gasket material.

Bennett

Todd320 · Dec 21, 2016

The IAC arrived, complete with gasket, no need to order gasket separately. Hope to install on Monday.

Brown Eyed Girl - 2007 Sea Ray 320 Sundancer, 350 MAG MPI V-drive

Todd320 · Dec 26, 2016

Installed IAC and IAC muffler/filter, super easy, engine cranked right up, no alarms. Thanks for everyone's help. I used a Sierra after market part, I will try to reply here if I have any issues with it.

Brown Eyed Girl - 2007 Sea Ray 320 Sundancer, 350 MAG MPI V-drive

mblockb · Aug 31, 2019

Realize this is a really old thread, but anyone have part numbers? 2004 340 Sundancer, 8.1 horizons non HO

Todd320 · Aug 31, 2019

I use mercruiserParts.com, and I input the serial number, then browse the diagrams until you locate it. Many times I order from there as well, unless trying an aftermarket part.

mblockb · Dec 11, 2019

Sharing some pics on this topic.
Pic 1. Dirty muffler in throttle body.
Pic 2. Dirty muffler removed.
Pic 3. Melted IAC.
PIC 4. New IAC installed.
Pic 5. Error message.
Super easy DIY repair. Changed the muffler on the other engine hoping to prevent melting the other IAC. Also have a spare IAC just in case. The Sierra 18-7701 part worked. Bought the OEM part as well just in case but did not need it.
1.