I think scary is an understatement.Dropping the key is not a problem provided the immobiliser chip has not come out of the key(not possible unless the key has opened up.Looks like the dealer is guessing at this fault .It is possible for the key to become de-synchronised if the car battery becomes very low voltage or flat ,but is an easy fix for the dealer.Very much doubt if this has corrupted the ecu.

This is getting more and more frustrating. The garage have had my car for a week now. They don't return my calls, but when I finally got someone to talk to me this afternoon he told me that their computer that's supposed to diagnose the problem won't talk to my car's ECU. They have now got a donor part from Honda, which they are trying. And if that doesn't work, then they'll try another donor part until they find a fix. I have no confidence that, even if this does get fixed, that I'll ever really know what went wrong and therefore will have no confidence that it won't go wrong again. I was just lucky that I was at home when it happened and not out driving my elderly disabled mother.

I came across an online magazine article about recalls on the Jazz because of ECU problems. So I put in a call to Honda customer service line for their advice and I'm waiting to hear back from them.

I think they think the car was jump started and this has caused the problem. But the RAC man didn't jump start the car! This time. About two years ago my battery went flat and the RAC jump started it then. I know the key was in the ignition when they did so, because I had to drive around a bit and then went home, where I had to switch the car off in the usual manner. But that was two years ago and I haven't had any problems until now. Could that event of two years back have caused this problem?

Thanks bolt.

I've just phoned the garage and they now say it wasn't the ECU. It was the immobilizer after all. Which is odd, because early this week they had replaced the immobilizer, but they said it wasn't that. Oh and it wasn't the key. Except now it was the key. Which is what the RAC man thought at the beginning.

Actually the garage are saying that the immobilizer damaged the key - or maybe the key damaged the immobilizer. They're not sure. So because I don't know what went wrong, I have no confidence that the immobilizer won't just kick in again ... potentially in a more tricky situation than when stationary on my drive.

The garage's diagnosis computer wouldn't talk to my car - I gather it still won't - and they don't know why, but they say they "saved me money" by getting donor parts and going through a process of elimination till they found the ones that made a difference.

It's now Friday the 12th and they've had my car since Thursday 4th. I've missed a trip to see my Mum for her birthday as a result. But at least I now know that public transport is hell on earth!! It's too late now for me to go and pick the car up today - the garage is MILES away and I have to catch several buses to get there. So it'll be tomorrow before I'll get it back.