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Hi everyone,
Firstly, great site with loads of info and knowledge available - keep up the good work!

OK - We have a 407 2.0 HDI (136) on a 54 plate. We got it around 83k miles about a year ago, and it's now done 88k miles. My wife uses it to work and back, thats it (about 20 miles a day - 40ish mph - non motorway). Not too sure of it's history, aside from hpi checks etc. when we brought it. It has a 'little' service history.
Since last year, I have had a mechanic friend do a ''service' - air/oil/fuel filters, oil change and cam belt renew. Also had to replace the ball joint for mot.

OK - here's the problem....and a little background.....3 weeks ago we got the dreaded depollution system fault. My mechanic friend suggested a couple of bottles of diesel redex, and a good 'blat' up the motorway to make it regen. Did this, and the fault disappeared - good!
Last Monday (the hottest day for years, and boy it WAS hot here in Kent) my wife drove it home from work and it flashed a warning symbol on the mfd that she tried to describe to me - I can tell you this symbol IS NOT in the pug handbook. I saw it when I went to look at the car - kind of an open beaker with a wavy line across - I was thinking maybe a low fluid resevoir somewhere. I looked about - all fluids good. I gave it a start, all fine. Then, after 2 minutes, it simply cut out, as though it had run out of fuel (which it had not!). Tried to start it again - nothing. It simply turned over (strong), but no start up, exactly like a lack of fuel. My mechanic came over, had a nosey about, and we found that there was a strange 'buzzing' coming from the ECU area of the engine - sometimes a few seconds, sometimes up to 10-/15 seconds. We disconnected the ECU - which was very hot - to the point that you could only hold it for 2 seconds before it hurt. After allowing it to cool for a bit we re-connected and it started straight away - then cut out again after a min or so. Anyway, we found that whenever this [random] buzzing noise was going with the ignition switched on, the car would not start, whenever the buzzing was not happening, it would start first time.
We left it for the night, and agreed to look this weekend. Yep - you guessed it, started first time, and ran for half an hour yesterday with no issues, no warnings, no problems?!?!?!?!
So - do you think it was simply the really hot day causing this problem, somehow overheating the brain or the system? I was initially thinking a sticky relay or something overheating in the ECU area, but I have discovered that the relay under the ECU is for the glow plugs, so not sure how that would prevent ignition completely? The ECU yesterday was simply 'warm' after running for 30 minutes. Nothing in the area was 'hot' at all. We checked for damage around the wiring looms, nothing. No sign of anything 'shorting out'.
Should point out that on that evening, we checked the (new) fuel filter, as at one point we got a mfd saying water in fuel filter - which we checked - there was not. We also got another depollution warning, which then disappeared. We also could see fuel flowing through the filter, and no air bubbles, so don't believe it was 'actually' a fuel issue.

Can anyone shed any light - or was it simply TOO hot that day?

Thanks in advance of any help thrown this way!

Darren
 
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we checked the (new) fuel filter, as at one point we got a mfd saying water in fuel filter - which we checked - there was not.
This was my first thoughts as reading down your post and trying to put an explanation to the symbol, but you've already done it :thumb:

Where is the ECU located?
 

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Hi JMKent

Thanks for the reply. The ECU in question (and rough location of the buzzing sound) is above the battery, top right of engine bay. Upon unscrewing the ECU, there is a relay (kind of double length) which I have found is for the glow plug heater, and what looks like an in-line fuse housing. To the right of the ECU, looking from above, is the fuse board and some relays underneath - but none seem 'hot'.

Confused.c o m !!!:eek:
 
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Hot day or not, it does get rather hot under the bonnet no matter what, so all these bits should be designed for it, so I would doubt that the heat outside would have affected things under the bonnet too much.

With most electrical things, heat normally means something sticking/shorting generating excess current which gets turned into heat. Maybe something is intermittently sticking, and in which case you'll unfortunately need luck on your side to identify it :thumb:
 

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JM - That's what I feared!

I'm guessing that there is nothing in the ECU that can 'stick', so 'hopefully' not that! Just trying to fathom what's in that area that could possibly malfunction and cause an 'apparent' fuel starvation.

Guess it's a case of letting it back on the road, and hope for no re-occurence huh!!

Still, got the good 'ol RAC boys if the worst comes to the worst and it conks out while on the road!

My mind is still coming back to the extreme heat - my car ('09 mazda 6 - sorry chaps!!) was recording 37 degrees here that day, and the pug had been parked out in that all day.
 

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This was my first thoughts as reading down your post and trying to put an explanation to the symbol, but you've already done it :thumb:

Where is the ECU located?
Update: It would appear that the symbol was suggesting that there was water in the fuel filter, as JM suggests. I saw it on the evening in question. We checked the filter, and my mechanic opened the drain at the bottom of the filter housing, releasing some fuel - no water present. He then re-primed the filter by squeezing the rubber thingy to get air bubbles out (thats techy talk, huh!).:D The fault code has not re-appeared.
 
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Don't read too much into the car temp reading of 37degC - they all read stupidly higher than actual when in the sun, and its not until you've driven for a couple of minutes that they read right.

We had 27-28degC here that weekend, and my 407 didn't have any problems in it - air con had to work well though :thumb:

Higher temperature should allow a diesel to start easier.

These cars are used in far hotter countries than the UK, so I would really doubt the heat of the day was the root cause.... may not have helped if there is an intermittent electrical problem, but I wouldn't think it be the sole cause though.

As you say, leave it go and see how the car runs for the next few days... you never know, we might get a decent summer and it can test your theory again :D
 
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