ive done everything! reset the ecu take off the negat held in the brake for 15 second cleaned my MAF cleared the code i'm running out of ideas. My CEL stays on and throws no codes. i had a misfire code and fixed the problem and the light turned off by itself and then came back on the next day. all the readers i used say no diagnostic codes. what could be the problem???

 

Possible bad ECU.

 

maybe a short?

 

Don't panic! You say you have read your blink codes and you keep getting a no problem code? Your engine may be detecting knocks, you could probably use a new Knock sensor, there is an ebay seller who offers them for ~$70 shipped. There are many write-ups for the replacement procedure here on the Org, it is an easy job if you have tools. The other strong possibility is that your TCM has detected a transmission malfunction and the CEL is notifying you that it is operating in failsafe mode. If you make plans to have your tranny serviced expect to have all your bearings replaced apart from any necessary repairs or fluid replacement, this kind of repair will likely run you in the neighborhood of $750-1250 depending on the technician's skill and how well he/she knows you. Of course, your specific situation will vary. Good luck!

 

hmm maybe haven't dne anything to my trany exept changed the fluid and I have a new knock sensor from ebay paid 85 for it when I first bought the car about 8 months ago and when I got it it had a knock sensor code as well as an o2 code I fixed those and it stayed off until another code came up for my 3rd o2 sensor I put an o2 sim on and ever since theres been no codes but the lights on and I know for a fact the o2 sim is installed correctly

 

Are you using the Nissan port or the OBD2 port to retrieve codes? The OBD2 port won't let you get much info, you can get a lot more info from the Nissan port but you will still need a good scan tool.

 

You still havent specified how you are reading your codes. You can check blink codes through the ECU diagnostic mode procedure found on the Org, or you'll need a good scan tool as nlmaxima has mentioned to get further insight into your issue.

 

get a real scan tool and clear/check the codes...theres a good chance you might just be doing something wrong and not know it.

not a chance.

 

I have been using an obd2 reader and which is which port? I only thought there was one?

 

on your car there is only one(kinda). theres an obd2 port for nissan specific scan tools, which is in the fuse box(grey). and theres the general obd2 port for any standard obd2 reader under the dash(white). the 95's have obd1 and obd2 ports (which in my mind is 2 different ports, rather than both being obd2).

 

umm....why?
It's very possible... If for some reason the circuit for the check engine light is grounded inside the ECU it'll cause the light to illuminate...easy... It's happened before in other cars I see no reason why it wouldn't happen in a Nissan.

What you need to do is just make sure your ECM has no codes in it at all. If you don't trust your scanner...go to a garage and ask them if they'll plug in their scanner just to clear the codes.

As long as no codes are read in your reader the next step would be is to disconnect the output wire from the ECU that goes to the MIL and make sure that with that wire disconnected that the light isn't on anymore. The easy way to do this is to disconnect the whole harness from the ECU .If it's still on then 2 reasons remain, its grounded between the ECU and the cluster, or the cluster has a problem inside it(very unlikely). If it goes off then you ruled out those problems and all that's really left is the ECU is bad. It's as easy as that...What is the whole reason that the MIL comes on?? Because there is codes stored in the ECU, of course. If there isn't any codes?? The ECU is bad or a wiring problem.

To those that don't believe me look at the schematic... it speaks for itself.
Adios...

 

but the thing is....its not like that. the ecu is not bad.

 

who invented the check engine light ? while the idea is brilliant I would still like to slap that person.

 

Seriously

KS will never turn on the CEL
TCM won't turn on CEL it will flash the O/D light

 

yea so i feel stupid as hell its not any of that. messing around with all the problems it could have been my friend come over with a real good reader and it reads a code for a high circut whatever...aka gut*** cat which should be gone with my o2 simulator i have but oh well nothing big thanks for all the help though guys if after i fix this and its still doing it...sh** i dunno

 

95's only have 2 DLCs - OBD2 and Consult, no OBD1, same as every USDM A32.

 

Just... take the bulb out

 

My check engine light has been on forever. But yesterday i put some gas in it and the light went off. Then today the dang thing came back on again. Any ideas???? Oh yeah and if theres any links that you know of please post them.

 

IF YOU DONT HAVE A SCANNER GO TO AUTO ZONE THEY WILL SCAN IT FOR FREE & TELL YOU EXACTLY WHAT CODES ARE COMING UP. OR YOU CAN BUY ONE FOR ABOUT 130.00 @ AUTO BARN