Hey everyone,
I own a 1996 Maxima with 104,000 miles on it. I have had for a little over a year, when I first got it it had 79,000 miles on it. Soon after getting it, the CEL came on. If I remember correctly it was throwing three codes: the knock sensor, and 704 and 705. I did replace the knock sensor, however I did nothing else, so the light stayed on. I purchased an OBD II scanner, to be able to turn off the CEL.
My goal was to trade the Max in by this point, but I realized that I don't want car payments and I would fix the Max.
Well for much of the past year whenever the CEL would come on, I would just use the scanner to shut off the light. I don't know how many times exactly I shut the light off, but it was often.

Well for the past few months the light never came back on, and again I didn't fix a thing! Well since I am now keeping the car I plugged the scanner in today, to see what codes it would throw, even with the CEL not lit. It refused to throw any codes, but the scanner has three lights, green=all good, red=codes exist, and yellow=monitor status or pending code present. The scanner lit the yellow light, but no codes. So did I damage something by turning the light off often? What can I do to get the codes, and I guess trip the light again?

Thanks,
Zack

 

By replacing the knock sensor, you may have fixed all of your issues. The other codes you got may be piggyback codes, ie triggered by the bad knock sensor. I don't remember what 704 and 705 are specifically.

I believe in the old addage "If it ain't broke, don't fix it." I wouldn't worry about anything unless you are experiencing some problems.

Do you see the CEL light come on when you put the key into the ON position (but not start the car)? If so, probably nothing is wrong.

 

I would doubt you damaged the ECU. If it were me, I'd go to an auto parts store and have them pull the codes (if there are any) for you with a different scanner.
I'm thinking you're probably fine though..

 

Yeah, when I did my KS, the rear o2 code that came up with it disappeared. It seems to be a fairly common thing.

 

But the thing is that the car would fail the emissions test, since here in NJ all systems must be "ready". And even after the knock sensor was fixed the light would still come on for a while. It is just weird. I will look later when I start it, if the light comes on with the key in the start position.


Zack

 

OK well before you actually start the car the light does come on. I called the tech line for the scanner, and he said that the system is still checking itself so that is why no codes come up. I asked why it would take 5+ months to check itself and trip the light? He had no answer. He did mention a drive cycle? He said to find out what the Maxima drive cycle is, and that will trip the system faster. Any ideas as t o the drive cycle? What is it?


Thanks,
Zack

 

bump

 

How to get car ready for emission testing - drive cycle explained.....(Owner's manual chapter 10-18)
1. Start the engine when the engine coolant
temperature gauge needle points to C. Allow
the engine to idle until the gauge needle
points between the C and H (normal operating
temperature).
2. Accelerate the vehicle to 55 MPH (88
km/h), then quickly release the accelerator
pedal completely and keep it released for at
least 6 seconds.
3. Quickly depress the accelerator pedal for a
moment, then drive the vehicle at a speed
of 53 to 60 MPH (86 to 96 km/h) for at least
5 minutes.
4. Stop the vehicle.
5. Accelerate the vehicle to 35 MPH (55 km/h)
and maintain the speed for 20 seconds.
6. Repeat steps 4 and 5 at least 3 times.
7. Accelerate the vehicle to 55 MPH (88 km/h)
and maintain the speed for at least 3 minutes.
8. Stop the vehicle and turn the engine off.
9. Repeat steps 1 through 8 at least one more
time.
If step 1 through 7 is interrupted, repeat the
preceding step. Any safe driving mode is acceptable
between steps. Do not stop the engine
until step 7 is completed.

 

Thanks!

This is going to be a PIA!

Zack

 

Bump! I still can't get the CEL to kick on. I know that the light works because it lights when the key is in the on position but not yet started. Any more ideas?



Thanks,
Zack

 

You can disconnect the battery and let the car sit for 24 hours, then reconnect the battery. This will reset the ECU, and possibly give you the CEL you are seeking shortly thereafter.

 

So have you trying to trip the cel by unplugging a couple of sensors?

 

Ok the battery is disconnected, so I will let it sit for a few days and see what happens.


Thanks,
Zack

 

i thought the knock sensor doesnt trip the CEL, i know in an infiniti i30's it doesnt trigger a CEL. I also know in 96 I30's its almost impossible to get the car into ready status., i think you were better off not clearing the knock sensor code but clearing the other two. Also by just disconnecting the battery isnt it just going to put the car back in to incomplete status?

 

I know that the knock sensor will not trip the CEL, however it also had the other codes. I would like to fix those now, but the damm light will not trip!


Zack

 

i thought you already pull the codes from before, why not just look up what the codes are that you pulled from before and just fix it, why wait till the cel turns back on?

 

Because I am not 100% sure what they were.


Zack