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[packratbimmer]

Th is might help from a 1992 Bosch catalog

[e30austin]

Is this the one that also controls the cold start injector?

no, that's the thermo time switch. the taller brass sensor.

[hurryupcole]

yellow temp sensor handles cold start to 20c. if that switch fails, it's always thinking it's in open loop. BMW no longer sells a correct switch as a replacement for the yellow one. the purple is a sender only, no switch involved. the "fix" is to eliminate it because it's absolutely pointless.

To my knowledge there are 4 on my thermostat housing. The ECU coolant sensor, the gauge coolant sensor, the thermo-time switch for cold start injection, and the 45 degree temp switch. Yes it is a 45 degree temp switch on eta cars and does play a part in idle. Mine is working properly it has been tested before, continuity when below 45 degrees and no continuity when above 45 degrees or vice versa I can't remember but it is in fact working properly. Do you mean to eliminate the ECU coolant sensor? And if so, you're right.. BMW doesn't sell a genuine replacement but many companies still make ECU temp sensors for eta cars. https://www.fcpeuro.com/products/eng...or-13621357414 This is the one I have on my car right now, it is a fairly new one.

[e30austin]

yes, there are 4, on the 325e.

- blue for coolant temperature up to 45c, the main fuel mixture control
- brown single pin for instrument cluster
- brown dual pin, thermo time for cold start injector
- yellow for coolant temperature up to 20c, dual pin, yellow top, this is the one you need to bypass

good luck

[hurryupcole]

yes, there are 4, on the 325e.

- blue for coolant temperature up to 45c, the main fuel mixture control
- brown single pin for instrument cluster
- brown dual pin, thermo time for cold start injector
- yellow for coolant temperature up to 20c, dual pin, yellow top, this is the one you need to bypass

good luck

Okay, so just to clarify again, you're telling me to bypass sensor 13 on this diagram?

[e30austin]

no. 15

[hurryupcole]

no. 15

Okay, 15 has been replaced with a new 45 degree temp switch and is working properly. A company makes these new I forget where they're located but here https://blackstarmanufacture.com/pro...t-temp-switch/

[emuguru]

Whoa thanks for the info guys, I checked mine again after reading this, I had checked it several times. But this time when I pulled the wires off it fell apart and I realized I've only checked it with the engine off, not vibrating. It had been corroded and separated, but when the engine was still it tested fine. After replacing with a jumper, the car idles soooo much better!!