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Had a CEL come on while driving home recently. It was Sunday so no garages were open and I made it home ok.
Next day and since then there's been no repeat. Is there something I can check on that might have been the cause?
I'm a bit concerned it could come on again at a bad time far from help....

Speak with your mechanic and have him check the error codes with an OBD reader.
Greg.

Does the CEL have to be on when checking the codes?

See above.

Silvia wrote:Does the CEL have to be on when checking the codes?

No, ECU stores error codes as long as the ECU is connected to a power source. Hence when the battery is disconnected & brake pedal pump a few times before reconnecting the battery, the error codes are cleared.

Note you also had a CEL problem back in April this year:
viewtopic.php?f=29&t=63021

Thanks Paul.

Good memory 93! Yes same CEL but I've been overseas 2 months. Car has been on trickle charge and battery not disconnected during that time. Would you advise to keep driving to see if it comes on again ? Is it possible to have a one-off warning that disappears? Mechanic told me to come back if light comes on again (though he was fairly busy that day)

Silvi,
If my memory serves me correctly, this is a repeat of the last CEL occurrence and you did nothing then, re-read the original thread and continue to drive the car after all it worked then.
Or you could check here.
http://www.dx.com/c/car-accessories-799 ... -tools-725
Greg.

That sounds like a great thing to have Greg.
It seems for about $12 I can self diagnose in future, but is there a catch?
Will it be right for the MX? Does taking a reading remove the code ? Can I find the socket?
Which one of the dozens listed does one order?

Start with a repair manual and then do some research, or talk to your busy mechanic when he is not.
Greg.

Ok, went to mechanic (German trained, on Mazda list for my area) and he said if there was anything seriously wrong CEL would re appear. Explained about computer reading Waves and if a wave ,particularly to do with pollution gear, went a bit above normal it would set off CEL . So basically don't worry unless it reappears. As a mechanic normally would love to have your car in his grip , I'm inclined to believe him.
I've checked all vital signs and it runs perfectly......

Fortunately, given your previous advice that your NB8C is an Oct 2002 build, your MX5 should be OBDII compliant.

Silvia wrote:It seems for about $12 I can self diagnose in future, but is there a catch?
Will it be right for the MX?
Yes, OBDII is an industry standard, ie not just Mazda.
Does taking a reading remove the code?
No, but I believe at least some have a delete function.
Can I find the socket?
Yes, remove fuse box panel in the driver side footwell (near where the right knee of a seated driver would be & look at the top & you'll find it.
Which one of the dozens listed does one order?
Your mission Silvia, should you choose to accept it...