Ever seen a temp sensor like this?

[ssaylor]

I've been experiencing a CEL flash every once in a great while while cruising on long distance trips. I was able to recover fault code #1223 from the ECU which indicates the coolant temp sensor is acting up. I asked the shop to replace it with a new, 2-pole PN 13621357414 but they discovered a 3-pole variety was installed instead. WTF? 2 wires from this connector go back to a relay mounted on the fuse box. The Tech said he followed one wire that headed off under the left front fender and thought it might be another fan relay or something. Does anyone know if this was a TSB fix for A/C cooling for something? Chances are disconnecting and cleaning that corrosion will take care of the fault codes but I'd really like to know what this is a solution for - and the part number for that 3-pole sensor! Isn't it fun working on 25 year old stuff?

[cmcgrogan]

part number 13621707366 is the three prong. thats what you need

[Poorboyz]

Can you maybe show a more zoomed out picture so I can try to see where in the engine bay that is located?

Sent from my Galaxy Nexus using Tapatalk 2

[ssaylor]

I see it - for the 750i & 850i? Any idea what this extra pole & relay are doing?

Thanks!

[cmcgrogan]

only two pins are used iirc

[cmcgrogan]

but now that i think about it, do you ahve an electric fan, maybe the 3rd pin goes to the relay which triggers an electric fan?

[ssaylor]

From the sensor, fingers on the leads into the relay, single wire out under the coolant overflow to the radiator area.

[cmcgrogan]

where do the other wires on the relay go? i know there are all types of relays, any chance you could find that out?

[ssaylor]

That's it! 2 go in and one comes out, as far as I can tell. There is an aux fan for the A/C. I just found a service receipt for a aux fan resistor replacement so I'm assuming it's for the fan.

Anyway, it I still log the CEL on my cruise to Monterey, I'll replace that 3-pole 2500 ohm sensor. Thanks for the PN!