# HELP! Altima SES Light Flashing!



## Luca Brazzi (Feb 7, 2006)

And the Engine seems to misfire at high speed!

Heres the story...

I recently changed the Plugs, Fuel Filter, and Air Filter on my girlfriends 1999 Altima.

After doing this, The SES light came on. The code indicated a MAF problem. I tried cleaning it, but that didnt work. I reset the computer by turning the screw on it clockwise, then counterclockwise. The steady light went out but now the car runs fine at low speeds, but jerks/misfires at highway cruising speed. The SES light also flashes while driving.


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## Luca Brazzi (Feb 7, 2006)

Luca Brazzi said:


> And the Engine seems to misfire at high speed!
> 
> Heres the story...
> 
> ...


Problem solved... SILLY ME! The ONE TIME I installed new plugs without checking the gap on each one... the plug I put in #4 cylinder was about .030 inches to close to the electrode! 

DOH! 

The way I figured it out was to put the ECU into diagnostic mode. It flashed 65 which is number 4 cyclinder misfiring. I pulled the plug and found the problem.

ALWAYS Gap your PLUGS! Dont rely on them being pre-gapped!


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## borsa_boy (Apr 7, 2005)

How do you put ECU in diagnostic mode?


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## Luca Brazzi (Feb 7, 2006)

borsa_boy said:


> How do you put ECU in diagnostic mode?



I did it by turning the car on (but not starting it) Then, I turned the screw on the side of the ECU fully clockwise, waited 2 seconds, then turned it back counterclockwise. The SES light started flashing the code... First Digit with long flashes, then short flashes for the remaining digit. It was flashing 65 which I looked up in the service manual to be #4 cyclinder misfiring.


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