A couple of months ago I ran through very dense mist on the M6, a few minutes later it threw up an emissions warning light, clearing almost immediately. The local Specialist had a thorough go over it, we found the EGR valves were sticking and as well as fitting a new oil cooler he did a remap to bypass the EGR valves.

It has run fine since.
I had a 240 mile uneventful run towing the caravan through torrential rain today - tonight driving solo I went through another similar spell of very dense mist with lots of different warning lights a few minutes later, suspension faults, transmission errors the lot.
I stopped and restarted it and it is fine.

My reckoning is there is moisture getting in somewhere - has anyone else had this problem? I have owned it for 7 years now and looked after it with no expense spared.


Any suggestions gratefully received!

Air inlet route all ok and well sealed and a good clean filter?

What are the errors saying ? Is it limited to just emissions (isolated fault) or across a range of systems, abs, emissions (i.e. common fault like bad earth) V8 or else ...

I had only one first time a few months ago - emissions.

TOnight I had
Engine management fault
Suspension inactive reduce by 6%
Limited gears (wouldnt pull at all)
Parking brake inactive

After stopping then restarting they all went.

Have you tested battery and alternator ? it may be coincidence that it happens in the mist? Probably not but at least it takes them out the equation _ I doubt if driving into mist would give any more water ingress than say following a truck one the motorway when it is raining

Another question was it mist or was it cold enough to be freezing fog?

The second set of errors points to multiple systems being affected, which to me indicates a common fault across the car.

As above, I'd now being looking at the electrical supply system. Low voltages often show up via transmission errors and ABS for the solenoid activations ... the auto gearboxes especially seem to want a really good supply to work properly.

Is the belt slipping on the alternator? this may be happening more in the very damp conditions.
Is the tensioner tensioning? You should be able to pry it freely to loosen pressure on the belt and it then snap back into place with decent force. V8 or else ...

It wasn’t freezing fog, just dense mist.
I think there may be a tone change on tickover, it seems a fraction more “whiny” which might give a pointer to the alternator idea. I use it every other day usually.

The battery must be about three years old, it is going in for Ian and the lads at Mike Aitken 4x4 to have a look at it.

Thanks for taking the time to chuck ideas about, apologies for not getting back sooner to check in.

Had the car back for a bit now and it is behaving itself now.
It needed two new air flow meters and with sticking EGR valves they got done too all showing up on the system as faults.
Then I had the humm up to 2000rpm and then just as predicted on other posts, a few weeks later the alternator went, so we did both alternator and battery.

The hints on this thread were almost spot on - alternator as a main cause in the end. The loading of demisters etc in the fog and the likes were obviously taxing the alternator, but it was not showing up in any other test as faulty, until it went terminal.

Thanks to all!