Peugeot 406 (1999 - 2004) - 03 2.0 Cooling fan running constantly

Honest John Back Room » Technical matters
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Mon 20 Jul 2009 05:03
03 2.0 Cooling fan running constantly - slugpug
Hi,

Problem with my 406 2.0 HDi.
The cooling fan runs as soon as the key is turned, regardless of engine temp.
Is it likely to be a sensor which is faulty, and where would i find it?

If I keep an eye on the temp guage would it be ok to run the car with the fan disconnected for short journeys, until I get it sorted as I've never heard the fan running before now, even on hot days. Seems this engine runs quite cool.

Cheers
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Tue 21 Jul 2009 14:26
03 2.0 Cooling fan running constantly - andrewuwe
Since no-one else answered...a different pug of mine had a faulty temp gauge screwed into the radiator, which made the fan run on even after the ignition was off. I disconnected the fan and ran like that for a year. I was very aware of the temperature in traffic jams.
I used to fly helicopters and when you do this you learn to regularly "sweep" across all gauges and dials. I don't think you would, I think you would forget, I think you would cook your engine.
But like I say, absolutely no problems, long journeys are fine too.
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Tue 21 Jul 2009 16:21
03 2.0 Cooling fan running constantly - Andrew-T
The HDi engine runs at about 80-90°C with a decent draught through the radiator, so long runs aren't a problem - and it won't warm up fully for 5 or 6 miles, so short runs aren't either. Even in a jam it won't overheat for a few minutes, but that would be your main worry.
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Tue 21 Jul 2009 16:40
03 2.0 Cooling fan running constantly - Armitage Shanks {p}
I had a version of this problem, in that my 307 fan would run on after I got home and parked up. Nothing odd showing on the temp gauge and not after a dash down a M way.The problem, such as it was, was cured by replacing a small electrical harness connecting the temp sensor and the fan switch and maybe the sensors as well; £25 + fitting as I recall

Edited by Armitage Shanks {p} on 21/07/2009 at 16:42

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Tue 21 Jul 2009 23:59
03 2.0 Cooling fan running constantly - steve_earwig
Sensor on the thermostat housing, I think it's blue (I could be wrong of course)
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Mon 7 Mar 2011 12:39
03 2.0 Cooling fan running constantly - BillDK

Here is how I solved the problem on my 406 HDI 2002.
The relay to the fan is placed just in front of the battery. It is clipsed on to the plastic box that contains the battery. Earlier when I has replaced the battery, I must have forgotten to clip on the relay again to the battery box.

A consequence of that is, that the relay has been hanging down and have been filled with water!! I placed the relay inside my house on a radiator for a night and the next day the fan works perfectly.

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