FAILED EMISSION TEST!?! 99 Nissan Max with 218,000 miles on her yet she still purrrrs like a kitten.?

Anywho she failed the emission test as I knew she would because the check engine light is on.





Does anyone know what the codes listed below mean in laymen terms? What has to be fixed? What effect they have on driving the car? Expected cost?





Also, if I get 1 of the 3 fixed will that allow me to pass the emission test?





P0325 - Knock Sensor 1 Circuit (Bank 1 or Single Sensor)


P0400 - Exhaust Gas Recirculation Flow


P1320 - no description was given


Thanks!|||The knock sensor detects pre-ignition and will retard the timing to prevent damage. So if you are seeing a code for it, the sensor has probably failed.





So that needs to be replaced.





The next code is what's called an EGR for short. It's common that this fails and causes a test to fail. It recirculates exhaust gas back into the engine to re-burn and keep emissions down.





The tech tests it, if it doesn't work, the car fails. So there are two ways to go here. The first option is to remove and clean the EGR. If the diaphram isn't damaged, you can save it. But understand it's clogged with carbon, and it's tough to remove. Otherwise, just replace it. One last note, it could appear to be bad if it isn't getting vaccum. Check vaccum hoses going to it.





The p1320 is a misfire code from what I could find on the net. It's probably related to the first knock sensor code. So the source of both these codes could be something causing a misfire. That would be a bad spark plug, bad spark plug wire, or you could even have a funky injector in that one cylinder.





Once the repairs are made, you'll need to clear the code with a code puller. You can usually find one on ebay (OBD II) for under 50 bucks.





Don't try to reset the light without fixing things, you won't fool the smog tech because the car gets connected to their computer and it will detect that the codes were recently cleared, and that codes are pending (meaning nothing was fixed)





After clearing the codes, you'll know the repairs are ok because the light won't come back on AND when you check again for codes, there will be no pending codes.