did i swap the right temp sensor?

[THEhomelessONE]

I know this thread is old but still useful information. So you used original e36 ECU temp sensor towards the front of engine and 2 prong m42 sensor in rear? Didn't know m42 also used single prong temp sensors.

[1991 e30 bmw 318is]

Ok it works the thread in the back sensor is different then the front. so it was the same as the m20 and m42, so i put the m42 sensor in it and it works. also got my electric fan in there it should kick in when it get up to temp, also have it on a switch.

Thanks for the help guys.

[1991 e30 bmw 318is]

they both should thread in. The m42 gauge temp sensor will screw right in. I am pretty sure the m20 is the same but am not 100% as I did not swap from a m20.

I think you have the sensors and /or plugs flipped flopped

yes the plugs were going to the right sensors there just in the opposite spot, so they should be fine. and i have the wrong m42 sensor, i have the 2 prong one i need the single. so ill call the guy with my motor and see if he will trade, he should because he will need the one i have. and i want the m42 one because it goes right in. the m20 one i would need to re thread.

[jakeb]

they both should thread in. The m42 gauge temp sensor will screw right in. I am pretty sure the m20 is the same but am not 100% as I did not swap from a m20.

I think you have the sensors and /or plugs flipped flopped

[1991 e30 bmw 318is]

You shouldn't have to rethread anything.

ok so the m42 sensor i have is good? if i was stuck using the m20 sensor i would need to rethread it. the m20 one is bigger.

[Fidhle007]

You shouldn't have to rethread anything.

[jakeb]

The m42 sensor will work and you do not need to rethread anything. If the gauge pegged than your wiring is good.

It looks like you have the wires plugged into the wrong sensors...

[1991 e30 bmw 318is]

I'm pretty sure that's an M42 ECU temp sensor, not the one for your gauge. You need a blue, double-prong one for the ECU (preferably for an E36) and then the brown M20 one you have will go to the gauge plug as is, even though it's wired for two.

that's what i thought. so i need to rethread it...

[Fidhle007]

I'm pretty sure that's an M42 ECU temp sensor, not the one for your gauge. You need a blue, double-prong one for the ECU (preferably for an E36) and then the brown M20 one you have will go to the gauge plug as is, even though it's wired for two.

[1991 e30 bmw 318is]

here are some pics of what i just did. i found the real wire for the gauge, by grounding it. it was on the black sensor on the back side. so the wire labeled with blue is going to the front sensor blue one also witch is the one i swapped the sensor in, from my m42. so that was the problem. so if i pull the black sensor out and put that one from my m42 back it there will it work? I'm still not sure that i have the right one from my m42 because it is a 2 prong. but it has the same threads so it fits right in, it would be nice if i just had to put it in the right place. here are pics.......

this made the tamp gauge go to hot...




and this is the m20 sensor....





and the m42 sensor i have....







m20 left ..... m42 right....




so is the problem just that I put the m42 sensor in the wrong spot? because i know people do use them from the m42.. if this is the wright one it would be nice because if I'm stuck using the m20 sensor then i need to make it fit...... or do i need a different m42 sensor?

[1991 e30 bmw 318is]

ok i just got the right one. brown single prong from an m20, so it goes in the front right? and i just use the stock e36 plug? and re thread it to make it fit?

[1991 e30 bmw 318is]

And you may not have it wired correctly.

And in your picture, you seem to have the plugs plugged into the wrong sensors.

The wire with the blue tape goes on the blue sensor, this is for your DME.

The other wire goes on the brown e30 sensor with only one pin. This pin needs to be connected to the coolant temp wire at your c101.

humm.. i know i never mixed them up, if they are it was like that because i never had both off at the same time. Too be sure i did not mix them up. going to the junk yard now to get the sensor off my old parts car....

[matt]

My guess is you haven't used the right sensor yet. It should be a single-prong with brown plastic.

And you may not have it wired correctly.

And in your picture, you seem to have the plugs plugged into the wrong sensors.

The wire with the blue tape goes on the blue sensor, this is for your DME.

The other wire goes on the brown e30 sensor with only one pin. This pin needs to be connected to the coolant temp wire at your c101.

[Fidhle007]

My guess is you haven't used the right sensor yet. It should be a single-prong with brown plastic.

[jakeb]

Or check for continuity from the sensor plug to your c101/x20 plug, make sure you have a connection there. Do you know how to check for that? can use a MM with either a beep check or resistance setting