When a vehicle is smog tested in California, several components of its exhaust gas are measured. If the levels of those exhaust gas components are within limits (presumably established by California), the vehicle will pass (barring any other issues).

Exhaust gas components tested include: NMOG, NOx, CO, PC and HCHO. Where does California publish the limits for these exhaust gas components? I assume there must exist some published tables for a given make, model, engine and year.

For example, the limits for a 2014 GM Gen IV 5.3L Engine are:

NMOG: 0.070, NOx: .04, CO: 2.1. PC: 0.01, HCHO: 0.011

I "scraped" these limits from a California ARB Executive Order. There must be a state website that lists these limits, but I cannot find it.

  • CARB was the source so contact them.
    – Solar Mike
    Mar 20, 2020 at 5:16
  • Start here: ww2.arb.ca.gov/homepage
    – Solar Mike
    Mar 20, 2020 at 7:47
  • @SolarMike - You know, I've just spent the last 20 minutes looking over that website and Google Searching and I don't see anywhere where it shows the actual standards. You'd think something would be there. Maybe I'll look more when I have time. I'll bet you their standards are a complete convoluted mess, because ... well ... that's California for you. Mar 20, 2020 at 13:06
  • @Pᴀᴜʟsᴛᴇʀ2 Back in the day I had to send them data each month about component failure rates...
    – Solar Mike
    Mar 20, 2020 at 13:22

1 Answer 1


I think I figured it out. Follow this link to the On-Road New Vehicle & Engine Certification Program page of California Air Resources Board's website. In the navigation panel on the left side of the page is the heading Program Links. Under that is a link to Executive Orders Listings. This shows multiple rows, each corresponding to a year. The first column is for cars, SUVs and light duty trucks. The row/column intersection contains a date that is also a link. Click on that date/link. This results in a page showing all the Executive Orders ("EOs") issued in the given year. The EOs are represented as links to PDF files containing the text of the EO. The EO's name encodes the vehicle manufacturer's name and the size of the engine and the revision number. It's not nearly as good as searching by make, model and engine, but the EO you want will be in that list. They give you tips for figuring out how the file names are constructed.

These are all the A series Executive Orders. I think they are submitted by the manufacturers, stating the levels of emissions for a given vehicle. These are not the D series Executive Orders, which list after market parts and work (like an engine swap).

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