I hate that blasted thing it makes you worry even if its nothing. But I go to my car yesterday after its been running and that light shows up. So I asked all around if anyone has a scanner and no they didn't so I had to deal with it. About an hour later it went away. My question is, does the ecu keep a history of codes? I'm just curious as to what it might be. Oxygen sensor was my first guess. But why would it then go away? It was really cold last night if you think that may be part of it.

I believe they do keep codes..

Could be a plethora of things though..

Is the car running differently at all?

SuFz :ninja:

ECU retains error codes, but oxygen sensor may not be one of them.
If the error clears, it means that whatever sensor was giving an out of range reading, has decided to behave itself.
Don't need a scanner to read error codes. Just a paper clip.

Google "Mitsubishi error codes".

for example: http://www.mivec.co.nz/tech/Mitsu_DiagCode.pdf

By the way, being a Diamante, you will have several oxy sensors. When it comes back, then you know you have an issue

By the way, being a Diamante, you will have several oxy sensors. When it comes back, then you know you have an issue

Oxygen sensor is just a random guess. I wouldn't put a spanner on the car until the error codes are read.
Could be a lot of things.
Playing mechanic and replacing bits on the "it could be this bit that is broken" is a waste of time.
The ECU is smart enough to want to tell you what is wrong, so why guess?

Yeah and the only reason I guessed oxy sensor was the fuel economy was suffering just a tad, still is as it seems. My test hasn't fully been completed. But I get at most 400 kilometers around town, and that's granny footing it. I also get this rumble sound under load at low rpms (that may very well be from the two resonator boxes I removed though, would follow suit with the fact I heard you lose low end just a bit. Pulls so much harder when I do get on it. Or the fact that its an old and tired motor.)
Car drove exactly the same.

Believe it or not the plugs were on the car from factory. Wonder if it may be time for cap n rotor? :P that wouldn't be the problem of course though.

One other question too, which is the popular open port cable version to get? Say if I wanted to read fuel ratios and maybe even flash the ecu n that stuff. Reset my idle speed to whAtever factory was cause I tweaked that screw so much. I searche but I didn't find a clear answer.

Found the error code yet? I'm interested.

One other question too, which is the popular open port cable version to get? Say if I wanted to read fuel ratios and maybe even flash the ecu n that stuff. Reset my idle speed to whAtever factory was cause I tweaked that screw so much. I searche but I didn't find a clear answer.

I have a ROM image from a 2001 model (as your profile indicates) which is for a 32bit ECU - these ECUs can easily be reflashed with the OpenPort 1.3U cable. The earlier models with the 16bit ECUs require an OpenPort 2.0 cable for reflashing. If you only want logging and DTC clearance, an OpenPort 1.3D will suffice. If in doubt, get the OpenPort 2.0 (pity its the most expensive... :()

See the thread linked in my sig for more information about reflashing.

I should add that your Diamante ECU supports the OBD2 protocol so many OBD2 scanning solutions should work for checking/clearing codes and logging. Evoscan (buy this when you get the OpenPort cable) can also log using the OBD2 protocol.

No error code showed up again yet. I read the auto store here will scan for free, so when it does I'm going there.
Thanks for the openport, flashing info.

I would be hooking up to a scanner, many codes do keep but if this comes again go to somewhere you can scan the car and DONT turn off the motor

For sure will do, see the car was idling for about a minute when it came on. So I'll be able to let it idle like that (warmed up right after driving) tonight.

So it came on, got it scanned . I believe he said that the warm up catalyst was below threshold. I didn't even think of asking the specific number but he said that it may be part of my idle being set too high which was another thing his scanner read. Unless he was thinking that the check engine light was the idle problem. But I just figured I'd open this old thread to post my findings.