I have a 2005 Nissan Frontier runs fine on most of the time. Other times after the engine warms up or even when cold the engine will dye, stall out, pops out through the throttle body. Check engine light has been on since this issue began. When I fill the truck up with gas the gas gauge returns to empty with the empty light on. Once I drive a little over 25 miles the gauge moves to barely below the full line and works okay until I refuel. This issue with the dying, stalling out, and pops do not appear every day. Some days it never occurs but today it happened 3 times. Usually after you shut off and restart 2 or 3 times the truck acts like it is finally getting gas instead of air and it runs fine. I went by Auto Zone and had them run codes. One was PO455 control system gross leak detected; two was PO430 Catalyst system efficiency below threshold – bank 2, three level sensor circuit high input. I can not afford to keep playing the guessing game on what the issue is and would love someone input to fix this. Any ideas on my issue?

SOURCE: 2000 maxima with 84,000 miles

the code means the converter on the side cyliner # 2 is not working like it should ,to check to be sure you need a scan tool and data from the front and rear o2 sesor cannot mimic each other if they do the converter is bad ,there are aftermarket converters for that car but they dont preform as well as the factoy one .

Daniel Dollive

• 315 Answers
• Posted on Dec 13, 2009

SOURCE: won't stay running upon starting in the morning

sounds like a vacuum leak is causing the problem. consider this. idle bypass valve can be going bad or is bad.

if the engine is getting weak fuel pressure you should see a fuel light come on when this occurs. indicating improper pressure, witch the car running quickly tap the gas pedal.

now dose the problem happen in only cold weather so far? or also hot?

if not then your fuel pressure regulator is faulty.

i suspect the fuel pressure regulator myself but this is a procedure to help you determine it.

Johnny Brown

• 5763 Answers
• Posted on Mar 05, 2010

SOURCE: code PO420 catalyst system efficiency below threshold

you may have a bad converter, its not cleaning the exhaust, but on the other hand a bad rear o2 sensor can also cause this problem,there is a wat to test but you would need a scan tool or scope,replace the other sensor, if light returns then replace the converter, no money lost, if you were to replace the converter the o2 sensors should also be replaced. you have 165000 miles it would be crazy not to replace sensor and install new cat, so basically your just doing it in 2 steps and may get lucky and not need a cat. good luck.

Testimonial: "Your information is exactly what I needed to know.I suppose I just did not want to spend the money for a cat. converter. Thanks again for your help. "

SOURCE: check engine light on

Diagnostic code produces P0420 catalyst system efficiency below threshold-Bank 1. Probable causes are listed as follows:
1-air leak in exhaust before rear 02 sensor, 3-Fuel system fault,
4-faulty catalytic converter.

SOURCE: what is catalyst efficiency below thresholds

you need a new catalytic converter...po420?