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Top Rated Merchant

Smogs Unlimited is a top merchant due to its average rating of 4.5 stars or higher based on a minimum of 400 ratings.

Smogs Unlimited

2133 Wylie Dr,, Modesto,

$20 for One Smog and Emissions Test at Smogs Unlimited ($54.95 Value)

Up to 63% Off
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Help Smogs Unlimited

Support this business with a RISK-FREE purchase. If you're unable to use your local Groupon, you can trade it in for use toward any of our other great local business - until you either view the voucher or it expires.

Highlights

Star Certified Technicians perform state-required smog and emissions test to ensure vehicles comply with regulations

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What You'll Get

The Deal

  • $20 for one smog/emissions test ($54.95 value)

Additional $10 fee for state certification and electronic transfer upon passing test.

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 120 days after purchase. Amount paid never expires. Additional $10.00 charge will apply for certificate if vehicle passes. $15 additional fee for vehicles from 1995 or older. Not valid or RVs and busses. Limit 1 per person, may buy 1 additional as gift(s). May be repurchased every 30 days. Must use promotional value in 1 visit(s). Valid only for option purchased. All goods or services must be used by the same person. Merchant is solely responsible to purchasers for the care and quality of the advertised goods and services.

Smogs Unlimited

Auto Repair & Maintenance, Inspection & Emission, Repair Service