I was looking under my hood this morning to diagnose a plastic resonant rattle I've been hearing from the engine compartment and noticed that this plug was not inserted into it's receptacle on the secondary intake box (directly below the plug as shown in the picture) to the left of the battery. Does anyone know what this plug is or what it does? I reinstalled the plug, but have no idea what it is.



While in there I also uninstalled a subwoofer amplifier power cable that the previous owner had left (live) running into my trunk connected to nothing. How considerate...

 

That appears to be your Incoming Air Temperature (IAT) Sensor. There should be a rubber plug with a hole just big enough to friction fit around that plug in the side of the air box just in front of the plug in your photo. If all you have is a big hole in the plastic box with no rubber seal/plug/bushing to hold the sensor ( I do not see the seal bushing in the photo and it should be visible), you'll have to get another seal.

In the meantime, unfiltered dirty air is being drawn into your engine through that empty hole. You are probably also hearing a high frequency whistle, without knowing that it isn't supposed to be there.

Edit: Now I see the seal bushing on the sensor. If the whole assembly fits tightly into the hole in the plastic air box, you're OK.

 

Manxman, thank you for your answer. Fortunately, the rubber seal was still in place and I was able to securely reinsert the plug. I'm really glad that I noticed this as the last thing I want is dirty air being sucked into my engine. Thanks again. This forum is a wonderful resource thanks to people like you.

 

its awounder you were not throwing any codes for it being poped out but i guess it should be fine unless its unplugged

 

Seriously. I'm surprised as well. Never had any codes or warning lights as far as I know.

 

it's just a temperature sensor, there's no way for it to know if it's inserted into the intake. It was just giving readings of the temperature of the engine bay. No harm done, though. Just plug that sucker in and keep an eye on it to make sure it doesn't pop out.

 

Kudos to Manxman for winning the engine compartment trivia question. I'd have ignorantly looked around for some appropriate orifice to shove that thing in. I tried to rep you but the site won't let me.

 

I appreciate the thought anyway- thanks.

 

You're welcome. Suggestion- watch eBay Motors in the parts for Honda Fits for anyone selling the Helms Honda Fit Service Manual (or, if you have the budget for it, buy a new one from Helms). With that, you can identify anything on your car and look up any specification you might need.

Ain't that right, feddup?

 

Absolutely right. did that ebay sale pass by? I used to get up at 2 AM to bid on stuff and eventually said "F&^% this". I mean it I'll eagerly pay $35.