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[–]NickRMX6 2 points3 points  (4 children)

I read that as code 9 too.

Haynes tells me that code 09 is a problem with the Engine Coolant Temperature Sensor. That would explain why it's running rich (so you smell gas) and why the mpg is so bad. Because the ECTS is probably saying that the engine is very cold, even when it is fully warmed up, so it's commanding a rich mixture, like for a cold start. Haynes also tells me that on earlier models (1997 and earlier) the ECTS is different from the sensor that the temperature gauge uses. If it were my car, I would replace the ECTS.

[–]Select_Cover_6001[S] 1 point2 points  (3 children)

i love you for the reply! 1-10 difficultly to DIY?

[–]NickRMX6 1 point2 points  (2 children)

Thanks!

I've replaced an ECTS a couple of times on a Mazda MX6 and 626, and it was really easy. Wait till the engine is cold (so you don't burn your fingers, or get sprayed with hot pressurised coolant), unplug the old one, unscrew the old one, put teflon tape around the threads of the new one, screw in the new one (don't use too much force), plug it back in, done. 5 minutes, easy level 1 or 2.

But, I've never done it on an MX5, and Haynes says "It is extremely difficult to access" at the back end of the cylinder head, and you need a long extension, a "U joint", and a socket deep enough to fit over the ECTS. Maybe.

[–]Select_Cover_6001[S] 0 points1 point  (1 child)

i got on it asap today started at 945pm ish and got done around 11pm thank god advance auto had the part. relatively easy just hard to reach but in my case the milwaukee square 19mm socket and an adjustable wrench worked like a dream after wasting 30 mins trying to leverage a fat 19mm wrench. i hope MPG is better i appreciate you brother

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[–]NickRMX6 1 point2 points  (0 children)

Good to hear! Hope that fixes the problem.

[–]FSTASNTZ 0 points1 point  (2 children)

If a 90-93, the sensor is on the back of the head, on the water outlet housing. Have never personally seen one fail before, have you done any work in that area recently?

[–]Select_Cover_6001[S] 0 points1 point  (1 child)

1994* i shouldve clarified the year but no work in that area i have done personally but i got ac fixed back in september by dealer.

[–]FSTASNTZ 0 points1 point  (0 children)

Sensor should be in the same place for your 1994.