I just figured I would share my experience fixing this problem. This seems to occur frequently enough.

If your airbag light comes on, it will first blink a code, repeat it, then go solid. In my case, the airbag light would flash 4 times, pause, flash 2 times, pause a little longer, repeat, then go solid. If you have a different code, you will have to find out what it stand for, then go from there to remedy the problem.

I found out that 42 is the code for the front impact severity sensor. Here it is -- it sits on the hood latch support, with a barcode on it.




To replace this, I first removed the battery negative terminal and waited a minute. Then I unplugged the sensor.



I removed the sensor and checked the pins and socket for corrosion. None found.




I checked the sensor for continuity, and didn't get anything. I probed the socket, and got a continuity beep on my DVOM.

NOTE: DO NOT EVER PROBE AN AIRBAG SYSTEM WITH YOUR BATTERY CONNECTED.

So, I ordered a new sensor from the local dealership ($52 total), replaced the sensor, plugged it up, reconnected the battery, started my truck, and the airbag light no longer came on.

Since I did not see any corrosion on the sensor's pins, I decided to perform a little destructive inspection. As you can see from the images below, water seems to find a way into the sensor and corrode circuit board components. Upon removing the cover from the sensor, I could see corrosion all over the PCB. I removed the PCB, checked underneath and in the housing itself and didn't really find any additional corrosion. The part number for the old sensor was 4L3A_14B006_AB. The replacement sensor is part number 6L3Z-14B004-AA. Hopefully, the updated part is sealed better.

 

Excellent work!

 

This just happened to me and I am about to replace this for 52 and change and I am wondering if we cant caulk it or something to make it last longer. My truck is an 05 with 60k and its bad already. Indiana uses a lot of salt and my connector is corroded. I cant believe ford didnt use a weatherpack connector on this since its right behind the grill out in the open. I am going to dielectric grease the connection and hope that keeps it from corroding.

 

I am about to get into the exact same project. But before I head downtown to buy all the gear, how did your dielectric grease work out? I havent seen any replies about the new part having any better weather seal or not so it seems to me that dielectric grease is the way to go. It cant hurt to over kill on protection can it? Kind of like a double positive?

 

I havent had another failure yet but I wouldnt have expected one either. I put the grease in the connectors and where it meets the frame. When I broke my old one apart it had lots of oxidation on the board so the whole unit needs sealed some how which I didn't try to fix.

 

That's good enough for me. thanks for the absolutely great post and pics Koharatx and Jeepville for the dielectric comment as well.

 

Wanted to say thanks for posting, had the same problem with my '03 Expo. I am currently serving overseas and anytime one of warning light comes on I cringe. Price for the sensor has gone up a bit, but $62 well spent. Once again, thanks for taking the time to pass on the word!

USAF MSgt
England

 

I have to let any of you Canadian readers out there know; If you are looking for the sensor here in Canada, it'll run you $120 CDN at the Ford dealers. I havent found one yet at NAPA or any other parts store.

 

Great post. Same problem here. I did have some corrosion on one of the pins (green monsters) I cleaned it up but still had 4-2 code. Change sensor and fixed problem..... btw it was regular $72 Cnd. and I got it for list @ $62.Cnd plus tax here.

 

Great thread!

I had the same problem myself this weekend for several days. It presented after I power washed the bugs off the front of my truck after a 400 mile road trip. It stayed lit for two days solid and then was intermittent the third day. Today was the fourth day since the wash and the issue was gone this AM on my way in. My truck is an 04 with 31k. The dealership told me to pack sand on covering the new one under the restraint warranty by the way.

I'm going to remove the sensor, store it in a container full of silica gel for a day or so to draw any of the remaining water I can out of it. Then I'll reseal the sensor's joints with silicone before putting it back on. Obviously water can now get in it.

FYI.....

 

Update, my light on the dash came on earlier this week again, so I just replaced it

Before installing the new one I resealed the entire seam around it with silicone gel, and then made a tin cover to go over the entire assembly. So much for that problem....

 

Hey Guys, I know its be a couple months for this post but I figured I would see if any of you are still out there. I have the same code 4 2. I pulled the sensor off and the prongs had a good amount of corrosion. Problem is the "female" connection has corrosion too. I ordered the sensor from Ford for $62 and change , it will be here tuesday. My concern is the "female" connection. Ford parts guy said I would likely have to order the whole wiring harness. Lets hear your thoughts, comments and suggestions.

 

How did you end up with this? I need the female connector also, I've had a hell of a time tracking one down.

 

I had no problems!.....I left the female side on and I cleaned it up real good .....the light reset and Im happy!