1999 Peugeot 406 2.0 HDI Overheating

Peugeot 406 Problem
The Problem
Fixes: 2
Apr 19, 2011 (8 years ago)
engine Overheating fans not kicking in at all whilst engine is gettig hot then the stop light starts flashing as temp reaches the 100 mark fans will only cut in if i unplug the thermo switch.
Any answers would be gratefull many thanks.

Car details
Car: Peugeot 406
Variant: 2.0 HDI
Model Year: 1999
Category: Electrics, ECU, Warnings & Lights

Recalls: Peugeot 406 Recalls
More: Peugeot 406 Problems
Replies and solutions
Fixes: 12,297
Apr 20, 2011 (8 years ago)
You should check previous posts section on this car with that problem , here is an example .


Since: Oct 2009
Posts: 396 | Fixes: 4219
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Suggested Solution

Posted on 2011 04 15

If you did as they suggested you could still have problems as a common fault on that car can be the relays / wiring or corrosion on connections or Bitron unit .This is a previous post on the same fault

Peugeot 406 overheating
The Problem
Car Peugeot 406 1.8
Year 1999
Owner john friend
Posted 25 06 2010

The Problem

can anyone tell me from when you start the engine how long would it take before the cooling fan cuts in
my 406 warms up very quickly,I have no water loss or mayo in cap

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Solution 1

Since: Oct 2009
Posts: 396 | Fixes: 4187
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Suggested Solution

Posted on 2010 06 25

This should give you the info required .

Wed 17 Aug 2005 15:00 Peugeot 406 cooling fans - P 2501
This is a very common problem. The two fans at the front should always run together, first at slow speeds with 6v and then if the temp stays high, they will switch to 12v and run fast.

Your non working fan has either a blown motor, or more likely, a bad relay.The other fan then compensates by always blowing on fast speed when the temp sensor actuates it.

The fans are turned on at approx 92 degrees for slow speed and 97 ish for high speed.The actual temps will be marked on the temp sensor which is screwed into the top right hand side of the rad (as viewed from the front of the car).

I had this exact problem and it turned out to be a corroded relay.On my 306 these were located in a triangular plastic box behind the front plastic grill in full view of road spray,rain,salt etc.No wonder they rusted! a bad bit of design really.

Something to get you started.
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Wed 17 Aug 2005 15:52 Peugeot 406 cooling fans - RichardW
"The fans are turned on at approx 92 degrees for slow speed and 97 ish for high speed.The actual temps will be marked on the temp sensor which is screwed into the top right hand side of the rad (as viewed from the front of the car)."

It won't be quite as simple as that on a 98 2.1TD - the fans are controlled by the Bitron unit (although this only handles the switching feeds to the relays which are still present as far as I know).

What should happen is that both fans come on slow at around 85°C, then both on high at a higher temperature (might be 100°C or so). When you switch the air con on both should come on on slow and stay on all the time the A/C is switched on. If the system detects high pressure or temperature in the A/C system then it should give high speed. Likewise of the coolant goes to the high speed temp you should get high speed.

If one fan is kaput, or there is a fault with the relays etc, then you may get only one fan on high speed when the high speed condition is reached. You should get nothing at all on low speed condition (fans are connected in series in that case).

If you are getting one fan on high speed when it should be low speed than someone's messed with the wiring.

The Bitron takes its feed from the brown sensor in the water outlet on the front of the head - if you unplug the sensor you should get both fans on full - even if the ignition is off.


and this link re. relays ,

406 STOP light
26 March 2006, 8:24 AM madmark
Joined 1 Apr 2005
379 posts

hi tony
your fault is caused by the engine cooling fans n/w
when the a/c is switched on the fans should also come on to keep the a/c gas in the a/c condensor cool
the fans should come on about 10 to 20 seconds after the a/c is switched on
check the fan relays for corrosion or broken wires
or fan speed resistor for an open circuit on one of the coils
both these items are on the front of the cooling fan housing behind the front bumper
i have also come across broken wires in the front vehicle harness
that runs across the bottom of the fan housing
but bumper removal is required to check and repair this
hope thisis of some help

peugeot tech

Fixes: 2
Aug 31, 2013 (6 years ago)
My stop light flashes on and off when driving. The engine is not hot or overheating as I have only just started up. Can anyone advice me plese
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