MX-5 OC Forum

 I can't seem to work out why the my Eunos makes a buzzing noise when I turn the igition on!

Its like some kind of warning sound (leaving lights on) What is this noise?

Also there is a light on the dash "HEAT" what is this about?

I got the original Eunos owners manual but even though it has some cool cartoon drawings I can't work it out!

Thanks, Grant

The heat light is something to do with the cat I believe!

Is the buzzing from the seat belt warning buzzer? Does it stop if you put your seatbelt on before you put the key in the ignition?

The buzzer is your seat belt warning. If you do your seat belt up before turning the ignition on you'll find it dosn't do it.

I just disconnected the wire that goes to the seat belt catch in mine, that stops it

The heat light, as has been said, is to do with your cat. The early Roadsters didn't have CO2, or lambda, sensors. Instead there was just a temperature sensor in the cat to show when the cat is overheating (I think). From what I've read these go wrong after only very low mileage and isn't really needed anyway, all it does is bring on the warning light. If you can get underneath you can see the sensor wires coming from the cat and there's a connector. Just disconnect this and forget it. Mine already had this disconnected when I got it and I then had to do some research to find out what it was for.

Dave

Just a wee correcton to that - all MX-5s, even the earliest, have a lambda sensor.  Eunos Roadsters also have a temperature sensor in the side of the catalytic converter.  As Dave describes, it's not needed and only lights that lamp in the dash if it's overheated.

The "Heat" sensor in the cat is actually a thermal fuse; it blows when the cat overheats (due to an over-rich mixture, like when a plug-lead's bad and the engine misfires). It's non-resettable so once it's blown, it's blown, leaving you with the dashboard light on. Like the guys say, just disconnect it, but be careful not to park on dry grass after you've had a misfire, 'cos the cat will be hot! Best bet - get rid of the cat!

Les

 Thanks, I know what these things are now!