My check engine light has been on steady since saturday. I did the self diagnosis 4 times, every time I got error code 4-9 (4 long pulses, 9 short), which is apparently undefined.

Has anyone else gotten this code before? what is it? should I just bite the bullet and take it to a dealer?

thanks,
Jesse

 

0409 is the Upstream O2 sensor circut slow response fault (right bank)....... Alot of the codes in the ECU decoder on the org are not filled in or "Undefined"

 

If that is the case, should I be worried about this? How difficult is it to replace that sensor?

thanks

 

I have heard that its not too difficult to replace the O2 sensors in the Maxima.....