406oc.co.uk

Hello everyone

Have a 03 406 HDI SE 2lt estate.
have a message on display "Engine temp to hot, stop" but the car has been parked for hours. Not a hot day, only happen when car as been parked. Any ideas ? time for a new thermostat ?

THanks

Hi and welcome, try a search on here but maybe check this thread out: viewtopic.php?f=10&t=1452&hilit=engine+ ... e+too+high

It's usually an electrical fault rather than the engine's coolant being too hot.

Replace the engine coolant temperature sensor located on the side of the cylinder head behind the air filter box...It's green.
Do this before looking at anything else.

Hi guys,

406 Rapier estate. 2.0 HDi 90 siemens.

Well I have this problem and I'm stumped... I've changed the Temperature sensor. I've tried tracing the wires (not easy) and finding relays and resistors, having looked at the above link my fan setup is different to the one pictured, so i really have no idea where to look for the resistors or any other ideas for me to investigate??

Regards

David

Hi Help please!!!

2003 406 Rapier Estate 2.0 HDi 90 Siemens

Same problem, I have changed the temperature sensor. Fault still registering, I have tried tracing the wires to find relays or resistors to check without success. This is driving me bonkers. The AC is not working correctly, the cooling fan is on full and does not change if I switch off the AC.

I have explored the area of the radiators for the resistors, but evidently my model is a different set up. I have also had my near side wing off and inner arches searching in there as another thread mentioned relays may be there.

Is it even worth my while changing the thermostat and coolant?

Advice and direction greatly appreciated please

Regards

David

Hi there, welcome

I've approved both your posts as they're different, Not to worry.

The instructions refer to an earlier car, yours is fully multiplexed and doesn't have any resistors, relays or anything. I suspect this is the diagram you're looking for:

cooling fan/mixer - engine ecu - engine fuse panel.

I'm not really sure what to suggest if you already changed the sensor (although never assume it's impossible to pick up another duff one). I'm not sure which way around the sensor works but what happens if you disconnect it?

Did you bleed the system after you changed it? The engine isn't actually overheating?

Steve,

Thanks for the post approval and reply. Yeah I have tried disconnecting the sensor, level sensor and all number of connections to try and get some sort of reaction, I even did a BSI reset. It is utterly melting my head.

I didn't bleed the system after changing the sensor, I've changed a few and have never had to, I'm pretty quick with the change.

I couldn't be 100% that it's not overheating as the gauge is not registering, but the oil temp gauge seems fine. It is also showing the fault first thing in the morning when all is definitely ok.

Wiring is my guess... But obviously a worst case scenario. Won't hurt to try another sensor.

David

As far as I can make out full muc cars use the same sensor for both the gauge and engine management so

Chippers2009 wrote:the gauge is not registering

seems a bit odd. may be something to do with it. I've no idea how though

FWIW mine does this too, only when the engine's cold and much more frequently on cool mornings.
I'm absolutely certain it's not overheating.
When it's playing up the idle speed goes to 1100/1200.
Did it most of last winter, then behaved itself all summer......

I got a new temp sensor a few weeks back, but so far it hasn't changed itself.

So my thoughts of dreading checking wiring will probably be the case

Well this morning I tried connecting another new sensor externally without effect, I decided to go and see someone with some electrical prowess, I nipped to work and left the engine running while I checked e-mails and chatted to colleagues before heading over to the maintenance guys. Low and behold on return to the car all was well bloody random faults! So I believe maybe the wax element inside the sensor needed time to warm and bed in??

But the main thing it is working now... Till next time!!

Mine is doing the same intermittently for about a year but the engine is not overheating. I need to change the green sensor and take it from there. I read somewhere on this site where the earth wire on the back of the instrument cluster can come loose and cause this problem.

I have had the same problem.
Bought a new sensor and plugged the cable into it without fitting the sensor, so as to test it cleared the intermittent STOP light / error message - which it did.
Reconnected to the original sensor, got the alarm again the next day.

Fitted new sensor yesterday.
For a 2.2 HDi, access is much better if you undo the TPS from it's bracket and move aside, (one screw). Also, remove the short flexible air pipe between the MAF and the 'elephant hose' that joins onto the turbo.
Obviously don't do it with a hot engine. Depressurise the cooling system by removing then refitting the expansion tank cap - to minimise coolant loss.
Have the new sensor ready with O ring in place, remove the retaining clip, pull out the old sensor and quickly shove in the new, refit clip.

Next, don't drop the bleed screw cap on the heater pipe like I did, occasioning another trip to the scrappy.
(If you do, a tyre valve dust cap nearly fits and will almost seal it while you marvel at your ham-fisted ineptitude).

Luck....