- My model of MX-5 is: 1999 MK2 Sport
- I’m based near: Derby
- I’m looking for technical help or recommendations on: Faulty water temperature sensor.Engine shuts down when stuck in traffic other than that the car runs fine.The engine fan cuts in as normal if i leave it ticking over on the drive.
If a water sensor has been diagnosed, then its a simple inexpensive replacement.
Any diagnostic fault codes present?
Firstly thank you for your replies.
Belle427 i believe there is no Diagnostic Port as such.
saz9961 i am working on the basis that my MK1 1.6 had a similar problem and it was a water rail sensor which cost £11.00.
The mk2 is a 1.8 engine and i do not know where the water rail sensor is located and what it looks like.Do i have to remove any thing to see it please?
Regards Ian.
All MX5s have a diagnostic port, NB models were OBD-II
Water rail sensor? You mean the water thermisters on the back of the cylinder head. Same sort on the BP engine.
I’d get codes read rather than guessing if the BP engine is the same as the B6 engine; its not.
B6 location
Look for the green sensor at the back of the engine.
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Hi saz9961, I believe that the early MK2 models use the same system as the MK1 mine has the same box located on the near side inner wing as the MK1 which operates a bit like morse code with flashing lights.
Regards Ian.
You can buy a little kit that consists of a shorting link, led and code description here to read the codes.
Sorry for the delay in getting back to you both a combination of the weather and my poor health has left me incapacitated.
I have found a tool made by MX5 Tech which i thought had been stolen when my garage was broken into and cleared. This has come up with the code 1345 Camshaft Position Sensor.
I dont know whether i have to replace it or just re position it to the correct gap .I have done nothing as yet because its too hot for me but will appreciate any advice offered.
Although the P1345 code is listed as “Camshaft position sensor” I believe it often indicates a problem with the the Crankshaft position sensor. (Since you mention adjusting its gap I guess you’re already familiar.) I gather it’s not uncommon to have these sensors become intermittent and heat seems to play a part in their demise. If it was me, I’d expect to have to replace it. Thankfully an aftermarket one is less than a quarter of the price of a Mazda one. (When I converted my Mk.1 engine to use Mk.2 sensors I bought the aftermarket type and it’s been rock solid so I’m inclined to trust them. I don’t doubt others will be along to caution otherwise.)
Sorry to hear that health and heat have been stopping you getting stuck in. Hope that improves soon and you can get your car back on form.
Hi Martin,
thank you for your reply i see now why i was deceived into believing that i have a coolent problem.
When i can see a traffic hold up approaching i turn the heater on full and the fan on max and it usually keeps the engine running otherwise it is a 25 minute wait before the engine will restart.
Am i right in assuming that i will have to remove the belly plate to get to the sensor to change it.?
Regards Ian.
My recollection is that yes the undertray needs to come off. It’s a while since I did the job but I seem to remember fiddling around from above before giving in and jacking the car up to get the tray off. Piece of cake when you go at it from below.
If it’s a possible crank sensor fault then I would check wiring to sensor before replacing it. When changing cam belt and water pump on mine shortly after getting it I found one of the engine anciliary drive belts had been rubbing on the sensor cable and had gone through to the cores. LuckilyI spotted it before it started causing an issue. The loom down front of engine runs close to the belt near the small water pipes about 1/2 way down.
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Thank You both for your advise i will get on with it as soon as it is cool enough for me and iwill report back to you on completion.
Kind Regards. Ian.
Job now done thanks to my Visually Impaired next door neighbors assistance.
I used the aftermarket sensor and as advised found the wiring very tight against the bottom pulley.
It is necessary to remove the undertray and i sheered off two of the bolts i will drill them out and re tap them oversize at a later date.
I am the third owner of this vehicle and have had it for six years,this sensor has been faulty all the time i have owned it the tick over is now rock solid and it starts better.
My sincere thanks for all advice from all parties.
Kind Regards.Ian
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Sounds like the temp sensor giving the wrong reading, easy to swap out.
M-m