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7 Days a Week Smog is a top merchant due to its average rating of 4.5 stars or higher based on a minimum of 400 ratings.

7 Days a Week Smog

$25 for a Smog Check for One Car at 7 Days a Week Smog ($79 Value)

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What You'll Get


The Deal

  • $25 for a smog check for one car ($79 value)

Catalytic Converters: Keeping Combustion Clean

Cleaner cars make for cleaner air. Learn how catalytic converters help with Groupon’s guide.

A car’s engine is a dirty place, and it produces even dirtier exhaust. Vapors exit the combustion chamber carrying a nasty trio of smog promoters: nitrogen oxides, hydrocarbons, and carbon monoxide. As these pollutants barrel through the exhaust manifold (the set of tubes that feeds exhaust from each cylinder into the exhaust pipe), there’s only one thing standing between them and the innocent air outside: the three-way catalytic converter.

Situated just before the muffler, the converter is home to honeycombed ceramic cores coated with some combination of platinum, rhodium, and palladium—three rare metals that interact with the main components of the pollutants. When exhaust enters, the metals trigger chemical reactions that heat the gasses and rearrange their molecules. Under their influence, nitrogen oxides splinter into pure oxygen and nitrogen, while hydrocarbons and carbon monoxide are oxidized into less-harmful carbon dioxide and simple water. Since their introduction during the 1975 model year, these unseen cleaners have made air more breathable and much tastier: the EPA estimates that cars built today are 98% cleaner than their counterparts from the 1960s.

The Fine Print


Promotional value expires 180 days after purchase. Amount paid never expires. Extra $8.25 fee for California state certification applies. Extra $15 fee per vehicle for 1999 models and older. Not valid for motorhomes, RVs, or buses. Re-tests not included with purchase. Appointment required. Limit 1 per person, may buy 1 additional as gift(s). Merchant's standard cancellation policy applies (any fees not to exceed voucher price). Merchant is solely responsible to purchasers for the care and quality of the advertised goods and services.

About 7 Days a Week Smog


7 Days a Week Smog

Auto Repair & Maintenance, Inspection & Emission, Repair Service
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