Service Engine Soon light and codes: P0325 P0440 P0446

[mr0x]

I was driving the day before yesterday night and the service engine soon light popped up. I went to Autozone and had them use the ODBII scanner to pull up the codes. The codes P0325 P0440 P0446 showed up.

P0325: Knock SensorP0440: Evaporative Emission (EVAP) Control System (Small Leak)P0446: Evaporative Emission (EVAP) Canister Vent Control Valve

The guy at Autozone said prolly your gas cap. I chceked the gas cap and when I removed the gas cap there was no pressure. No wooumph when I removed the gas cap - almost like it was just sitting on top rather than making it airtight.

I found some other discussions about this code:http://www.obd-codes.com/forum...=4139

and a good writeup about the Nissan evaporative system.http://www.asashop.org/autoinc...s.htm

I guess I will start with the gas cap. Any idea on a good quality gas cap? Also, any idea on a good quality EDBII scanner to reset the light?

I wanted one to connect to USB or bluetooth to my computer but they're all only shipping from China on ebay.

Thank you.

[loystock]

I edited your post. Link to competing forum is not allowed.

P0325 is for the Knock Sensor but will not turn on the CEL. So the CEL is due to 'evap' problem. Make sure you buy OEM gas cap as the aftermarket cap may not seal properly. Check the area around the gas cap for corrosion and clean as required. Also check all the tubes/hoses connected to the evap cansiter for loose connections, cracks, etc. Make sure you label the tubes/hoses to ensure you don't interchange them.

As for OBD II scanner, basic ones can be had for @ $60. Those with real time data cost >$100. Harbor Freight sells reasonably priced scanners.

Verify alternator charging voltage is in spec (14.1-14.7 VDC) as a failing alternator can give all sorts of problems.

[NutriaforBreakfast]

The floor shop manual can show you how to check the gas cap