View Full Version : help my "check engine soon" light came on.

04-14-2001, 04:32 AM
mY "CHECK ENGINE SOON" light came on.
Is there somthing wrong? I have 34,000 miles on her now. My friend said it could be set to go on at a certain millage is that true?
I have a 1997 SE 5-speed. Only mod is a stillen knn. Also will the KNN void my warenty? thank you in advance.

04-14-2001, 06:27 AM
If you go to nissan they will overcharge you on a diagnostic check. Thats the only way youll get that light turned off. My advice is to go to mechanic that works on imports a whole lot cheaper) and get them to run a dignostic on your computer to see what is wrong. If it is a major problem, take your car to nissan and pay the money to have them fix it, if it is nothing, dont worry about it. But to be honest, usually if the check engine light comes on it is definitely something wrong. So if you want to have it done wright just go to nissan and have them fix the problem. Pay the money its worth it in the long run and you can always take it back if the problem they fixed persists.

[This message has been edited by joemoody (edited 04-14-2001).]

04-14-2001, 06:35 AM
It runs real good. Seems the same as always.
execpt for the light being on. It came on just as I was pulling into english town(race way park) I ran anyway. Also my car I still covered by the factory bumper to bumper and
the power train/ drive train warennties.

04-14-2001, 09:38 AM
Yeah, just diagnose your ECU.. its not too hard, instructions are on the 240SX CCA site..

However, according to your mileage I'de suspect its your Oxygen Sensor (o2-sensor). Have you noticed bad mileage and sluggish driveability? That would be your #1 suspect.. especially if your car is stock. I just changed mine yesterday, took me 2 minutes.

- Mike

04-14-2001, 10:04 AM
I have had the car since july of 2000.
I am not sure about it being a slug. She feels quick. But my MPG has never been higher then 22 mpg. Thats driving conservtive. worst was like 19 mpg.
thank for the help!
I will check the 240sx.org FAQ

04-14-2001, 10:31 AM
Hey I was just wondering does the light stay on or does it turn off. My check engine light came on once, but then it never did it again, and the engine only has 20,000 miles on it. Should this be something to be concerned about?

04-14-2001, 10:44 AM
mine stayed on. I would think that if it is off you'd be ok but I dont know. anybody?

04-15-2001, 01:47 PM
Sure your car should have no problem if the Engine light's off.

From your mileage 22mpg or 19mpg I also agree is your O2 sensor cuz mine runs about 24mpg and 27mpg all Highway and nissan vehcile have the tendance to replace the O2 sensor once in few years.

The KNN filter itself will not void the warrenty but if you have the Stillen kit that would be difference. Suggest you to take it out before bring back to dealer.

The self-diagnostic feature in the ECU is one good easy to use tool to check what's wrong so turn to the dealer rightaway.

04-16-2001, 07:31 AM
I have The KNN cone filter from Stillen.
It is like the Jim wolf one. Would that void the warenty? Does stillen offer one like Ingen that would void the warenty. Or would both void warrenty.

The KNN filter itself will not void the warrenty but if you have the Stillen kit that would be difference. Suggest you to take it out before bring back to dealer.

04-16-2001, 12:05 PM
Speaking of MPG's, im driving HARD in the city.. full throttle everywhere I go, love hearing my engine.. BUT, I usually get anywhere from 16-20mpg's. I usually get 220-240 miles from my 14 gallons when the light turns on. Remember folks, there's TONS of traffic in LA.

However, as of 2 days ago.. I swapped in a generic Bosche o2 sensor thinking that would solve my stumbling on light accelleration. Amazingly enough, I've got like 200 miles on my odomoter with a tad less than 1/2 a tank! Man, makes me wonder how efficient my old o2 sensor was. I'm curious to see the results of my gas mileage in the future with the new sensor.

04-16-2001, 12:16 PM
sh!t, I've been getting really terrible mileage too.. maybe I should change the O2 sensor... my C.E. light has been on and off for a long time as well. When I took it to a mechanic a long time ago, I believe they told me it was a smog system problem, and not to worry until I smog the car. Could this be the O2 sensor? What else could set the light on?

04-16-2001, 12:30 PM
Does anyone have the part number for the Bosch replacement o2 sensor? What kinda price do you find for them? Are they a direct replacement or do you need to splice some wires?


04-16-2001, 01:22 PM
I also replaced my old 02 sensor with a Bosch....sparkling difference. i went from 20mpg to 26mpg. i paid about 40 dollars from pep boys. i don't remember the part number. and yes, it is a direct replacement, it even already has the antiseize compound on the threads. so unscrew that old POS sensor, pop in the new one, and reap the rewards http://www.freshalloy.com/

04-16-2001, 01:24 PM
oh, and about that check engine light....
i worked at enterprise this summer, and a common occurence for the check engine lights to come on. Solution: make sure the gas cap is clicked on all the way. worked about 90% of the time. (majority of the rental cars were american, so sometimes it was due to other things) http://www.freshalloy.com/

04-16-2001, 02:20 PM
Sidenote: o2 sensors

My original o2 sensor's tip looked like a small smooth pointy thing. The replacement is wide "fluted" with ridges and is thicker.

Any difference between the two? Is one a direct replacement for the other?

04-16-2001, 03:33 PM
i've heard (but can't verify) that the stock Nissan O2 sensor is just a repackaged Bosch unit.

04-18-2001, 09:52 AM
Well I went to 240sx.org and tried to pull codes from ECU as instructed by the FAQ.
Mine was set up a bit different. 3 screws instead of 2. one was actually a 10mm nut.
The ecu did nothing. We could not even find an led on it. were there different ecu's for different years? Any mid-year changes?
the check engine light did not blink.

MaxType 240
04-18-2001, 05:29 PM
I checked my '95 SE CPU today. You will in fact need the 10mm socket plus the screwdriver. Once loose, you'll have to access the side that is originally facing the firewall (towards engine). There, you'll find the selector and LED (recessed in a hole).
Good Luck...

04-18-2001, 05:41 PM
<BLOCKQUOTE><font size="1" face="Verdana, Arial[/img]quote:</font><HR>Originally posted by Eyescream:
i've heard (but can't verify) that the stock Nissan O2 sensor is just a repackaged Bosch unit.<HR></BLOCKQUOTE>

Indeed it is, with a tiny NISSAN insignia stamped on the sensor. Other than that, its repackaged BOSCHE product.

NISSAN = ~40-50 wholesale
BOSCHE = 25-30 retail autozone

Simple to install. Just get the universal and crimp a connector onto it, very VERY simple. Almost TOO simple.

Handle it like a sparkplug, be SURE not to get any oil, dirt, or anti-sieze inside the sensor.

04-18-2001, 06:27 PM
mine is always on before i start it, but when i start it, it goes off again. i dunno whats the deal

04-18-2001, 10:34 PM
240silviax-Might be your emmisions. Exhaust leak somewhere.
1997 240 sx se-Gas Cap. Have the dealer reset your warning light if you go in for a major service. That way its free.

S-14 Pilot http://www.freshalloy.com/

MaxType 240
04-19-2001, 08:33 AM
Once the key is at the ignition position, the light is supposed to be on just like every other illuminated indicator. Once the car is running they should all be off.