Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Overview of the National Low Emission Vehicle Program: Notes
Emission Reduction Stages:
While OBD II has the function of monitoring for emission related faults and alerting the operator of the vehicle, the National Low Emission Vehicle Program requires a certain number of vehicles produced (specific to manufacturing totals) currently comply with the following emission stages;
TLEV : Transitional Low Emission Vehicle
LEV: Low Emission Vehicle
ULEV: Ultra Low Emission Vehicle.
Prior to the National Low Emission Vehicle Program, the most stringent exhaust reduction compliancy is what is known internally within BMW as HC II . The benefit of exhaust emission reductions that the National Low Emission Vehicle Program provides compared with the HC II standard is as follows:
TLEV- 50% cleaner.
LEV- 70% cleaner.
ULEV -84% cleaner.
- Compliance Level
- NMHC Non Methane Hydrocarbon
- CO Carbon Monoxide
- NOx Oxide(s) of Nitrogen
- TLEV
- 0.250
- 3.4
- 0.4
- LEV
- 0.131
- 3.4
- 0.2
- ULEV
- 0.040
- 1.7
- 0.2
- Compliance Level
- NMHC Non Methane Hydrocarbon
- CO Carbon Monoxide
- NOx Oxide(s) of Nitrogen
- TLEV
- 0.125
- 3.4
- 0.4
- LEV
- 0.075
- 3.4
- 0.2
- ULEV
- 0.040
- 1.7
- 0.2
- Compliance Level
- NMHC Non Methane Hydrocarbon
- CO Carbon Monoxide
- NOx Oxide(s) of Nitrogen
- TLEV
- 0.156
- 4.2
- 0.6
- LEV
- 0.090
- 4.2
- 0.3
- ULEV
- 0.055
- 2.1
- 0.3
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.