Comments on: Faulty temperature sensor in BMW E36

By: Tony Sticks

Tony Sticks — Sun, 13 Jul 2008 06:21:46 +0000

@Steve Kaminski: I did exactly the same thing. I found 2 wires that were cut and seemed like they should be connected to something near the air duct. I connected them to the temp sensor and drove around a little bit and I noticed that the temp reading started to change.

By: Steve Kaminski

Steve Kaminski — Sun, 13 Jul 2008 03:43:19 +0000

My ‘94 325i is reading “-35 F.” So I bought a replacement sensor. Here’s the problem: this car doesn’t have brake ducts and, I suspect, is missing this sensor entirely. There are two small wires near the driver’s side fog light that look like they may be for the sensor. The carry a low voltage even when the ignition is off.

Do you think these are the correct wires for the temp sensor? If not, how else could I go about finding it?
Thanks!

By: BMW E36 OBC Showing -35F or -37C Temperature | BMW E36 Blog

BMW E36 OBC Showing -35F or -37C Temperature | BMW E36 Blog — Wed, 14 May 2008 13:38:03 +0000

[...] published the post Faulty temperature sensor in BMW E36 long time ago. The post talked about the reason why your OBC shows a wrong external temperature [...]

By: Tony Sticks

Tony Sticks — Sat, 08 Sep 2007 12:29:05 +0000

Rico,

There should be a plastic tube in the openning where the temperature sensor is located that should isolate the air in this area from the engine compartment. Did you check if this tube is still there because this tube usually falls out of the car. If your sensor is not isolated from the engine, then it’s most likely it will read a higher temp value.

By: Rico

Rico — Sat, 08 Sep 2007 00:40:17 +0000

You are right I confused the topic here. Still, it is how I said it. My car always reads a too high value for external temp. and that is very common. I searched it in Google and found several threads with the same problem.
I wish I could fix that. But moving the sensor somewhere else is not easy at all.

By: Tony Sticks

Tony Sticks — Sat, 08 Sep 2007 00:17:39 +0000

Hi Rico,

The procedure above suggests that you have to change the temp sensor only if the reading on your OBC is (-37C or -35F) and that value is not changing in either hot or cold weather. If it’s different than that (changing), it may be reading the temperature value correctly, hence, doesn’t need to be changed at all.

It doesn’t make sense that the engine heat will have a major effect on the sensor reading because the temp sensor is almost isolated from the engine compartment (see image above). It may have some effect, but I doubt it would be that great.

By: riCo

riCo — Thu, 06 Sep 2007 14:04:18 +0000

Hi Tony,
I have the same problem and it seems to be very common for the e36 series.
However, I read online that is has to do with the position of the sensor, not with a malfunction of the sensor itself.
When you drive slowly in city traffic, heat from the enginge goes everywhere under the hood and eventually the sensor starts reading wrong temps, influenced by the engine heat.

Please tell me if changing the sensor helped for you.

Thanks, Ric