occasionally i get a CEL light while driving but it doesnt come back once i turn the ignition on and off. How am i supposed to check it if im supposed to turn the ignition off to jump the ECU so i can count the CEL flashes? If i turn off the car it doesnt come back for days or weeks at a time!! yesterday it turned on while driving home from work as soon as i got home i jumped the ecu to check it and the damn thing is gone!!

its a 92 sedan d15b7 5spd.

 

why dont you go scan it then?? autozone does it for free or take it to a shop they can do it for free too

 

AutoZone can't scan an OBDI ECU.

 

When the CEL turns ON, leave the engine running while you jump the service connector.

 

AutoZone can't scan an OBDI ECU.

^^^^ thats what i was about to say.

 

are u sure thats ok? because i wanted to do that but i was afraid id fry something...

 

Pulling CEL codes with the engine idling is fine. Just don't drive the car with the service connector jumped.

By the way, is the BACKUP fuse under the hood blown?

 

ill go outside and check right now. dont think it is. i checked all fuses and relays a couple of months ago...

 

I asked because, if the BACKUP fuse is blown, the ECU can't store codes.

 

Check your oil level..

Weird enough, but if you ain't got no oil, and you try to veee-tak the VTC pressure switch disables VTEC and tells you that you're a dumb *** that's about to blow your motor cause you don't have enough pressure to run VTEC much less drive..

It's happened to me a couple times on REALLY nasty turns on a mountain run while in VTEC.. Only I was a half Quart low.. Not 2-3 QT like I've seen some people..

It's not a hard code and resets with Key off cycle.. Just throwin it out there.

 

no the fuse is good. ever since i bought the car my speedometer and cruise control havent worked, due to my speed sensor being bad. This CEL just started a couple of months ago but could it be related? also it usually happens when i drive for a while on the highway, I usually go no more than 3000 rpms....

 

thanks for the response but its a non-vtec and my oil level is right at the marker.

 

anyone?

 

If you throw a cell and your speedo doesn't work it's probably a code 17 VSS signal.. it's not a hard code and would do the same thing..

 

^ yup..speed sensor code will come after driving the vehicle. OP just answered his own question.

 

When it comes on do you notice a loss in performance and notice the engine run less smoothly? (ECU going into limp mode)

I had this problem, and I did what RonJ mentioned with jumping the connector when the engine was already on and the CEL came on... CEL wouldn't give me a code. Turned out to be that my ECU was screwed up. Got a new one and haven't had the problem since.

 

yea i guess ur right. i hadnt thought about it since my speed sensor hasnt worked since dec. when i bought the car and the CEL just started a couple of months ago.

 

no it doesnt go into limp mode. just the light turns on and its annoying as hell.

 

Well FIX your VSS.. I don't know how, but they sometimes get water in the plugs and the terminals rot off.. If this is the case, you might need to source a good VSS plug from the junk yard and wire it in.. One case I've seen a perfect looking VSS plug, and VSS sensor and you have a non-op or intermittent speedo.. The problem was a broken spring contact in the plug itself! I replaced the plug and the VSS worked perfectly..

Inspect, and replace as necessary..

 

well i agree i should replace the VSS but what im wondering is shouldnt it come on everytime i drive? drove about 120 miles round trip this weekend and been driving everywhere and the CEL hasnt turned on since i made this thread...

 

Its easy on the OBD 1 system. (On board Diagnostics Generation 1) Located by your ecu, passenger kick pannel, look for 2 hanging plugs, you want the one that only has 2 connections. Grab a wire and short these 2 terminals. Turn you engine on, but do not start the car. Start to count the flashes. Look closely for a long flash is a 10 and a short flash is 1. So if it blinks (Long) once, (Long) twice, 2 quick flashes.....that is a 22 and will be your Vtec Oil Pressure Switch issue. (just an example...dunno if your is v-tech or not.

The reason your light goes out when you shut off the car and restart it is this....OBD 1 (depending on the car) has a what is called a "drive cycle" they on board computer will throw a light when, once again depending on the program, will turn on the light if it reads a sensor out of range for any given length of time. If your sensor is bad, but it goes back into range and does not go out again durring this cycle, it will not turn on the light. If the switch registers out of range over the limit programmed the light will come on. If the switch is completly out of range upon start up and does not cycle....it will "hard code" and stay on.

Hope this helped.
P.