I bought my 2016 Fit EX used. I just recently started to use the auto headlight function since it got dark earlier. I found that my headlights were always ON and most distractingly, the interior lights would go on and it’s so dim in the day that I can’t even read the radio and dash.

I figured I’d try replacing the auto headlight sensor (aka sentinel sensor) with a new one since I didn’t want to deal with a used sensor that could possibly have the same sensitivity problem.

The part number needed per my Honda Dealer is 39860-TR0-A51 so I replaced it. It was a really easy swap.

So far so good. The headlights aren’t on as soon as I start the car like before. I placed something on top of the sensor and the lights go on like they’re supposed to.

 

$216 for a photodiode. I swear Honda just adds a couple zeros when going from production cost to sale price.

I wonder how the sum-of-all-parts price would compare to the dealer price?

 

I paid closer to $60 but I get your point. But isn't that how it goes with most cars? I wonder if the repair manual covers how to test this sensor...

 

Good info...i do use the AUTO fuction...i probaly would not have noticed for years.

 

 

You sure you're not referring to the Daytime Running Lights?

When I start my 2015 EX the Daytime Running Lights immediately go on.

 

He's talking about the "AUTO" position on the headlight switch. It judges ambient brightness using the sensor at the front center of the dash board, switching on the headlights and parking lights when it's dark enough. The system's daytime mode uses DRLs just as though the headlight switch were in the OFF position, the night time mode is just as though the switch were in the headlights position. The system also leaves the lights on for a minute or so when the car is turned off while in night mode, as a courtesy feature.