Mechanics

SERVICE ENGINE SOON LIGHT

2004 Nissan Frontier

Computer problem
2004 Nissan Frontier 4 cyl Two Wheel Drive Automatic 100000 miles

Truck is running normal
Service Engine Soon light came on, took to a " Autozone" Got error code
P0420
" Catalyst Efficiency Below Threshold"
Bank 1.
Replaced up-stream (engine manifold) Oxygen Sensor With Universal fit 3 wire, 1 white 2 black O2 sensor. Reused original plug from old O2 sensor, making sure to rewire it the same as to original.
Took back to Autozone, cleared error code. Ran truck at highway speed for about a 1/2 hour, Service Engine Soon light came back on.
Now what? HELP!
I'm trying to avoid taking it in to be serviced, if I can. Don't have the $$.
Thank you for any help!
Avatar
Idiver
October 12, 2010.




A dirty MAF sensor can cause this code to appear as well. Make sure MAF sensor is clean, if its OK then the cat. Converter may need flow tested, if its clogged or partial clogged it will also throw this trouble code.

Bluelightnin6
Oct 12, 2010.
Sorry, I'm not a mechanic. What, and were is a MAF sensor? Is there some-wear I can get a PDF image?
Thank you
Idiver

Tiny
Idiver
Oct 12, 2010.
MAF is mass airflow sensor which senses the incoming air into the engine. assuming you have the 2.4L engine, it will be located on the right side of the engine, near the throttle body (pic below). http://www.2carpros.com/articles/how-to-replace-a-mass-air-flow-sensor-maf


http://www.2carpros.com/forum/automotive_pictures/261618_Noname_2774.jpg


Bluelightnin6
Oct 12, 2010.
I'll give it a shot.
Thank you
AD

Tiny
Idiver
Oct 12, 2010.

AD