NOM-167-SEMARNAT-2017 is the Mexican official standard that establishes the maximum permissible pollutant emission limits for in-use motor vehicles operating within the Megalopolis. If you drive in Mexico City or its surrounding area, or if you run a shop that serves customers in that region, this standard directly determines whether a vehicle passes the emissions test and which hologram sticker it receives. At AM Exhaust we manufacture catalytic converters and exhaust systems designed to help a vehicle meet these limits, so understanding NOM-167-SEMARNAT-2017 is essential for both the driver and the technician.
What NOM-167-SEMARNAT-2017 is and who it applies to
Published in the Official Gazette of the Federation in September 2017, this standard sets the maximum permissible emission limits for tailpipe pollutant gases from in-use vehicles powered by gasoline, liquefied petroleum gas (LP), natural gas, and diesel. It also defines the test methods used to evaluate those limits and the specifications for hologram stickers and information technologies.
Its geographic scope is the region known as the Megalopolis, coordinated by the Megalopolis Environmental Commission (CAMe). It applies to vehicles operating in the following states:
- Mexico City
- State of Mexico
- Hidalgo
- Morelos
- Puebla
- Tlaxcala
It covers private and public service vehicles, whether federally or locally registered, regardless of whether they are used for cargo, passenger transport, or personal use, as long as they run on the fuels listed above.
Which pollutants and limits it regulates
The standard does not apply a single limit to every vehicle equally. It groups vehicles by model year, fuel type, and level of emission control technology, and it defines different values for each group. The newer and better equipped the vehicle, the stricter the limits it must meet. The pollutants evaluated are:
- Carbon monoxide (CO): a gas produced by incomplete combustion.
- Hydrocarbons (HC): unburned fuel that exits through the tailpipe.
- Nitrogen oxides (NOx): generated by the high temperatures of combustion.
- Particulates and opacity: relevant mainly in diesel vehicles.
Test methods
To measure those pollutants, the standard provides for different tests depending on the type of vehicle:
- Dynamic test: performed on a dynamometer, simulating real driving conditions. It is the most demanding.
- Static test: measures emissions at idle and during acceleration at medium speed, without a dynamometer.
- Opacity test: specific to diesel vehicles, it measures the smoke emitted.
Relationship with vehicle emissions testing and hologram stickers
This is where NOM-167-SEMARNAT-2017 affects the driver's wallet and daily routine. Vehicle emissions testing is the mandatory process in which an authorized center measures your car's emissions and compares them against the limits in this standard. The result determines the hologram sticker you receive and, with it, your driving restrictions:
- Hologram 00 and 0: the lowest emissions, greater driving freedom, and exemption from the Hoy No Circula program.
- Hologram 1 and 2: emissions within limits but with driving restrictions according to the schedule.
- Rejection: if the vehicle exceeds the limits, it receives no hologram until it is repaired and retested.
One figure that shows the real impact of the standard: with its implementation, around 1.9 million vehicles in the Megalopolis lost their zero hologram because the criteria became stricter. This means that many cars that previously drove without any issue must now keep their emission systems in top condition to retain a good hologram.
Why it matters to the driver
For those behind the wheel, complying with NOM-167 is not just about avoiding a fine. A vehicle that fails the emissions test cannot drive freely, loses resale value, and is usually burning more fuel than it should. The most common causes of rejection are directly linked to the exhaust and emission control systems:
- A clogged, damaged, or missing catalytic converter.
- Failed oxygen sensors.
- Leaks in the exhaust system that distort the reading.
- Misfires or a poor air-fuel mixture.
A catalytic converter in good condition is the first line of defense for reducing CO, HC, and NOx. If yours has reached the end of its service life, replacing it with a quality unit can be the difference between passing the emissions test or being unable to drive.
Why it matters to the shop
For repair shops, NOM-167-SEMARNAT-2017 is both a service opportunity and a commitment to quality. Correctly diagnosing why a vehicle fails the emissions test, and resolving it with parts that truly comply, builds customer loyalty. Recommending and installing catalytic converters and mufflers designed to meet the emission limits prevents the hassle of taking back a car that fails again.
At AM Exhaust, as a Mexican manufacturer, we produce converters and exhaust systems with controlled forming, welding, and leak-testing processes, so that the component you install helps the vehicle stay within the standard. You can check the coverage for each model in our applications section.
How to prepare for the emissions test
Whether you are a driver or a technician, these steps reduce the risk of rejection:
- Make sure there are no warning lights on (Check Engine).
- Check the condition of the catalytic converter and the oxygen sensors.
- Inspect the exhaust for leaks or perforations.
- Perform a tune-up with the engine at operating temperature.
- Use quality parts that meet emission specifications.
NOM-167-SEMARNAT-2017 is not meant to make your life harder: its goal is to protect the air quality for millions of people. Keeping your vehicle within the standard is good for your wallet, your car, and the environment.
If your vehicle did not pass the emissions test, or your shop needs catalytic converters and exhaust systems built to comply with NOM-167, explore our catalog in the store or reach out through our contact page. At AM Exhaust, we help you drive in compliance.
