Mx5 1992 mk1 temperature gauge issues

First of all not 100% sure if this is the right category, please correct me if it’s in the wrong place.

I have a 1992 eunos and within the past couple drives the temperature gauge has died on me! Occasionally it will work intermittently (constantly on and off especially when the road is bumpy). But the majority of the time the needle on the gauge just stays low. Has anyone had this issue before?

I’m looking at changing the green temp sensor in the rear of the engine but I don’t wanna waste money buying the sensor if it’s likely to be something else causing the issue.

If its a Eunos, I would pop off the instrument shroud, and check the multiplugs are fully in place, and maybe even whip out the gauges and make sure the screws are all tight. For every single Roadster out there, someone would have been in at the gauges at some point to sort out the speedo face. So not everything might have gone back together. Next check the sensor connector; it gets oily and hot back there, so the connection might not be great. And you are looking at the wrong sensor. Sensors usually work or they don’t, rather than being intermittant. So its likely a loose conntection/ bad earth.


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If it’s become intermittent then it’s very likely a poor connection and the easiest place to start is probably to wiggle the connector on the sensor and see if that magically fixes it. But as SAZ says, make sure you look at the right sensor as the gauge and ECU sensors are separate in Mk.1 cars.

@Martin_Young & @saz9961 thanks for your replies, glad I didn’t waste my money buying a new sensor :slight_smile: I’ll check out the connections and if that doesn’t work the gauges.

The sensors are cheap, but your knuckles will thank you.

@saz9961 @Martin_Young
So, I found the issue. Happened to be some dodgy souldering on the back of the gauge cluster.

so I fixed that, put the cluster back with all 4 connections (3 electrical plugs and 1 speedo cable thingy) turned the engine on and now none of the gauges work however the lights which tell you if the lights are on or off are now working. Any ideas?

An idea might be that you need a new gauge cluster. They are cheap to buy.

@saz9961, any idea why the old one may have completely stopped working? Would prefer not to buy a fresh one as I suspect it may be some sort of electrical issue, can see myself wasting money on fresh one and having the same issue and the miles being out.

Seems to me someone damaged the thin PCB… You can swap your speedo into the replacement st. Its a 2 minute job. Its only held in by a few screws.

If your photo is the repair you made, it seems that its shorting out.

If you believe some other fault in the car is causing damage to the PCB, probably bet to get an autoelectrician in.

@saz9961, ah okay, didn’t realise you could mix and match. Thank you for the advice as always!

Make sure it comes from a 1991-93 Roadster.

Are the uk spec clocks cross compatible with a eunos of the same year?

No. I know, from experience, Canadian clocks won’t work; the guages work, but the PCBs are different. On the case of your cluster, you should be able to find a code. Autolinkuk have different coded clusters on their website, and maybe someone here can say which year complete clusters are compatible. But UK cars won’t have the “heat” light and that screws things up. Canadian cars, a random find in an Irish yard, have an engine check light, but that difference ensured nothing worked…


I’m “fairly” certain any cluster from a 5-speed 1.6 Eunos will work for you, but the very earliest will be missing the light for the hard top demister, and autos might have a few funky differences. I know1.8 temperature gauges are different, and obviously later cars have the on/off oil pressure gauge.