So my CEL came on today, and I am due to register the car next month which means it's time for an emissions test.

I pulled these OBD codes

P0141 HO2S-12 Bank 1 Sensor 2 Heater Circuit Malfunction.

P0325 Knock Sensor

P0450 Evap Control System Pressure

Can someone give some insight on how to tackle these, where I should start, and the best place to buy these sensors?

Thanks?

 

P0142 - bank 1 is next to the firewall. Sensor 2 is after the pre cat in the y-pipe. This sensor is called the "downstream" sensor in parts stores. The exact location depends on the year of your car and whether it is Federal or California emissions.

P0450 - this is behind the driver's side rear wheel by the gas tank. Click on the link below and go to page 15. There are 4 diagrams. Look at the lower right diagram. At the top center is the EVAP Control system pressure sensor.

P0325 - knock sensor. Ignore this for now. This code shows up with any other code. 99 times out of 100 it is a false code. Fix the other 2 problems, reset the check engine light and the P0325 will probably be gone.

rockauto.com is the best place to get the O2 sensor. The EVAP Control system pressure sensor is probably something you will have to get at the dealer. Don't know for sure, though.

 

I currently have 2 evap codes, 1 egr code and a Vehicle speed sensor code. Knowing that neither of these codes will harm the environment or cause harm to my engine I decided to cheat my Illinois emissions and reset the codes with my app on my smartphone. Much cheaper just to do it this way instead of paying hundreds of dollars to fix some silly evap code that'll just end up coming back next year.

 

Some evap problems do allow gasoline fumes to vent into the atmosphere, so they could be harmful. Twenty year old parts are going to fail. A new part will last just as long, not just a year.