2 Sensors - 2 Similar Part Numbers - What Goes Where
 

I just received 2 sensors this week on different days from the same order. They look alike with same coupler and have similar part numbers:

PN41-18-840 = WATER TEMP SENSOR (green 2 contact) $47
NF02-18-840 = WATER TEMP SENSOR (green 2 contact) $28

What I bought them for is:
1. to replace the water temp sensor located on the back of the thermostat housing (active in fuel control). oem is green 2 contacts
2. to replace the water temp sensor located on the front side of the thermostat housing (active in cooling fan control). oem is brown 1 contact

Obviously, the 2 connector wont work the single receptacle
Anyone know which goes where. Are they the same connector different years?

thanks,
chuck

The only brown one on the front of the thermostat housing is for the Automatic transmission temp sensor (one wire, brown connector) the manual transmission thermostat housings don't have a temperature probe on the front of the themostat housing at all.

Green connectors== one will be the water temp for the rear of the water pump housing .The other green connector under the hood is the gasoline temp on the sec fuel rail . The one wire black plastic thing in front of the thermostat housing with a white connector is the water level sensor .

NF02 is the one on the back of the thermostat housing above the fan thermoswitch (single pin). I know this because I just replaced it last week. The other one SHOULD be the one in the fuel rail. Dealers have a tendency to get these confused and always try to sell you the wrong one.

Chuck, I had the same confusion as the diagrams aren’t clear. I believe that #N370-18-840 is the single wire sensor for the AT transmission, #NF02-18-840 is the green plug two wire for either AT or MT, and N391-18-840 is the two wire green plug sensor on the fuel rail.

Thanks for info guys.

The packaging for both sensors was labeled water temp sensor. Only visible difference was the greens were different.

I finally got around to pulling all the components above the sensor I did install (PN41-18-840), to do a VOM test. Ohm load at same temp was same for both sensors and they were within spec'd range as per the Mazda service manual (2.5 kohms). Im going to call Ray at Malloy and ask him what I got exactly and where they belong.
chuck

ps - Jeff, are you working on your engine problem. Any luck yet?