1.6HDI false overheating warning

[Robho]

I have a 2006 1.6 HDI. 

From time to time the red overheating symbol and "STOP" flashes up on the dash along with the beeping alarm. 

In my year's ownership (and c. 8000 miles) the engine has never overheated - if anything it runs on the cool side. 

Coolant is full and does not change.

When the fault occurs the temperature gauge shows normal running temp. I have had my local garage use their Snap-on tester which shows the temp. gauge is reading accurately - and their are no faults logged showing any issues.

In terms of frequency I suppose it on average happens every couple of weeks.

Its a bit annoying for me but, understandably, it unsettles my wife especially since we live in a rural area with several local routes heavily trafficked with lorries and really aren't safe to pull over and get out of your vehicle.

I'd appreciate any guidance on where to look (and any fixes) please.

Thanks
rob

[bikerbaker]

Had this happen to my 2004 2.0Hdi a couple of years ago. It was also a recurring intermittent fault. Took it to a local French car specialist who replaced a temperature sensor. I don't have the part number or the bill as the car was used for 3 years by a friend and she paid for it. About £120 I think which she thought was a real bargain as she also had a B Class and had paid £300 for a new sensor on that a couple of weeks before. 

Might be worth mentioning that it was only one of quite a few warning light issues she had. This was the only one that needed a fix. Fluid level warnings on everything due to the fact that the car was kept on her front drive, parked sideways on a steep slope. I was forever popping over to check fluids but all it needed was a few miles.

Touch wood, had it back for 6 months and it's all fine again.

[oilyrag]

You could try bleeding the system as there may be a pocket of air, possibly at the stat. It costs nothing and may be a long shot.....but whenever I'd had trouble bleeding mine the same symbol/warning appears.
Good luck!

[Robho]

You could try bleeding the system as there may be a pocket of air, possibly at the stat. It costs nothing and may be a long shot.....but whenever I'd had trouble bleeding mine the same symbol/warning appears.
Good luck!

Cheers both

One further factor I missed in the original.

It occurs most frequently when restarting after the vehicle has been used and parked for a bit (for us, typically dog walking)...su left for about 20-40mins, than restarted. I'll keep a note, from now see if I can be more specific.

[Kieron G]

On the M49 there is a level sensor in the header tank which I have had intermittent faults with putting a red dash light on. Also if the header tank is dirty inside that can put it on. Is very easy to unplug to see if that is the cause but like I said that's on M49 so I don't know if is applicable to 1.6 hdi

[Robho]

On the M49 there is a level sensor in the header tank which I have had intermittent faults with putting a red dash light on. Also if the header tank is dirty inside that can put it on. Is very easy to unplug to see if that is the cause but like I said that's on M49 so I don't know if is applicable to 1.6 hdi

Thanks - I'll take a look.

[Robho]

On the M49 there is a level sensor in the header tank which I have had intermittent faults with putting a red dash light on. Also if the header tank is dirty inside that can put it on. Is very easy to unplug to see if that is the cause but like I said that's on M49 so I don't know if is applicable to 1.6 hdi

Thanks - I'll take a look.

[Robho]

Following Kieron's advice, there is a level sensor on the 1.6HDi which can be removed. Gave it a thorough clean and flushed the coolant header tank...and, after two weeks, no more 'false alarms'!

On the M49 there is a level sensor in the header tank which I have had intermittent faults with putting a red dash light on. Also if the header tank is dirty inside that can put it on. Is very easy to unplug to see if that is the cause but like I said that's on M49 so I don't know if is applicable to 1.6 hdi