Blue Coolant Sensor

Tue May 31, 2011 1:40 pm

Hi folks I need some advice. My 325i cabby is running very rich when cold, theres a strong smell of pettrol both in the engine bay and from the exhaust.

I checked the resistance on the blue sensor at cold and its reading 1600 and about 300 when warm, from what I have read on the forums it should be about 3000 when cold.

So the questions are:

1. Should I replace it?
2. There is only 1 listed on the GSF web site which says brown is this the right one?

Tue May 31, 2011 1:55 pm

From Bentley,section 6,page 26...

-10C 7000-11600 ohms
20C 2100-2900 ohms
80C 270-400 ohms

Brown GSF sensor is for the gauge,the blue one is for the ECU,GSF do supply,but you may be better off buying from the dealer.

Tue May 31, 2011 1:58 pm

Thanks Daimlerman, looks like I need to call the local steeler.

Tue May 31, 2011 3:47 pm

Just got a quote from cotswald £23.59, does that sound about right? Seems a bit expensive.

Tue May 31, 2011 4:30 pm

Rtaylor2208 wrote:Just got a quote from cotswald £23.59, does that sound about right? Seems a bit expensive.

That's about right,GSF blue one cost me about £16,and did not cure the problem....

Tue May 31, 2011 6:10 pm

sorry to but in .but did you then fit a dealer supplied one and did that fix your problem?

Tue May 31, 2011 7:13 pm

gjj107 wrote:sorry to but in .but did you then fit a dealer supplied one and did that fix your problem?

Ermmmmmm,no!

This was concerning the instalation of an M50 engine into my touring,I had rich-running issues from the off,finally nailed down to a poor engine earth.

This left me with three blue sensors(original,GSF and dealer)one was used with the M50 and the other two put on the shelf.

I then had rich-running issues with the 2.7,and this time checked the resistance of the sensor against the table I posted above,this showed that the sensor had failed in it's cold position,so one of the 'spares' was fitted.
This cured the problem for only a few weeks,so the 'other' spare was fitted...
Now I am not certain which two of three I am currently using,but I am guessing that the one that ran for only a few weeks is the GSF one,and that the two in use are original BMW supplied items.

Hence my suggestion that the BMW-supplied item only costs a few quid more and may well be better value for money long-term.

Regarding the M50,one of the problems I had with this sensor is getting at the thing,all but impossible to get a meter on it's terminals,particularly with a hot engine,now,of course,I learn that another way to test it is at the ECU plug....