So a couple of times my Bosch P38 has refused to start - not immobiliser related, as it would sometimes start and die, or attempt to fire and fail etc. Until yesterday, it hadn't done it for months. I figured yesterday, it was because it was reallllly low on petrol and on a slope. Forced it to start on gas, and with my foot on the floor, it eventually went, but ran horribly for a little bit. Figured that was normal - cold vapouriser etc. It started fine once I'd moved the car, so I thought nothing of it.

Went to leave work today and..... it wouldn't start. Not on petrol or gas. I leave the Nanocom in the car now, so I plugged it in and initially went to check the immobiliser when I noticed...

For a cold engine... and even an up to temp engine, something looked a bit amiss here. Popped the bonnet and poked the sensor wiring/plug a bit as best I could. Got back in the car, and the reading had dropped to a far more reasonable 28c - car had been sat in the sun, so I went with it. Started straight away. I left the Nanocom plugged in though, and I noticed on my way home the reading would only ever show 59c, usually when at a standstill, or 85.5 when on the move. The gearbox had also resorted to jolting forward when coming to a stop - something it used to do a few months ago but stopped without me noticing. The idle would also jump up 2-300revs when the reading dropped too, which it often does randomly when its damp out.

Back home, A/C compressor unbolted and out of the way, I could actually get at the plug to check it out. Think I found the problem:

Red and green/blue wires both suffering insulation breakdown and shorting out on each other.

And fixed. Cut the plug off, soldered on some short flying leads and then reattached to the loom. I drowned the joints at the plug in resin so any vibration shouldn't cause any breakages etc. Best I could do without a replacement plug from another loom, short of just taping up the broken insulation and hoping for the best.

Coolant temperature faults cleared in the engine and gearbox ECU and all is back to normal, and my slight idle vibration also appears to be gone! Idle hasn't been shooting up either, though we'll see tomorrow when its cold and probably damp again if this was also causing that. Amazing how many problems a little bit of dodgy wiring can cause. I love how the Nanocom description states the fault would light the MIL. Nope. Even unpluged, no MIL - and it does work.

That's a new one, on a GEMS, the wires break off where they come out of the plug so you get open circuit and the temp sensors think it's -40!

Shows the value of a Nano though. Would have taken bloody ages to find otherwise!

Nice post, thank you.

The Nanocom has definitely paid for itself already, I wouldn't be without it now. In diagnostic plugins alone between this car and my parents I've saved money over going to a dealer.

To be honest at ~£330, for what it can do its a bargain... especially considering it isn't VIN locked or any rubbish like that. A Syncmate is £150 on its own isn't it?

Why do we never see second hand Nanocoms for sale? Is it maybe that those that have them dont sell the RR because they are able to fix them rather than get shot of it.

Hey Sloth, Ive just noticed that your from Poole/Bournemouth. I lived in Highcliffe until 2 years ago.

Sloth, if you have any problems, I have an engine loom that I've butchered for some of the plugs, I know I haven't cut that one off yet,, fingers crossed its all ok, but keep me in mind if you need the sensor plug,, Chris

I was about to ask where you are now... then I saw your sig, bit of a move! :)

Thanks for the offer Chris - I think I should be okay, so far all is behaving itself and no more idle shooting up either!

Now, if it would like to give me a little bit of a break from problems like this, I might be able to get around to taking the intake off and doing the rocker cover gaskets. Losing quite a bit out of them now and the exposed bits feel very hard, so I guess its been a while. GEMS definitely has the advantage here in accessibility...