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  • Mitsubishi Fuso Authorized Dealer
    Established 1967
  • 1505 N 4th St. San Jose, CA
  • 408-263-7300
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Smoke Emissions – Opacity Testing – San Jose

Certified Bay Area Opacity Testing at Diamond Service

The California Periodic Smoke Inspection Program requires that heavy duty trucks and buses over 6000 lbs. gross vehicle rating be tested yearly for smoke emissions (opacity testing). If your vehicle or fleet is due, Diamond Sales is a great choice for annual Bay Area opacity testing.

  • We are approved by the California Air Resources Board as a Certified Smoke Testing Facility. Our technicians have received college-level training and have CARB-verified opacity testing certificates.
  • We provide you with required documentation of the results of your test and make record keeping easy by maintaining copies of your documentation in case you need a replacement.

Opacity Testing in our shop:

  • Truck: $109
  • Bus: $149
  • Mobile Opacity Testing is available. Call for quote.
San Jose Opacity Testing: Causes of Excessive Smoke

If your engine is pre 1991 and has a smoke opacity of 55% or higher, you’ll need to have repairs done or be subject to citation.

If your engine is 1991 or newer and has a smoke opacity greater than 40%, you are subject to citation unless repairs are made.

The usual causes of excessive smoke are:

  • Injection pump timing
  • Elevated maximum fuel rate
  • Fuel pump calibration
  • Problems with smoke puff limiters
Diamond Service Provides San Jose Opacity Testing and Repairs

As a certified San Jose Opacity Testing location, we’re also highly qualified to repair your engine and get the opacity back to where it should be. We evaluate the cause of excessive smoke, make appropriate repairs, verify your vehicle passes, and get you back on the road.

If you’ve been cited, we can get you the repairs and Demonstration of Correction form you need to get back to business. Remember, you have just 45 days from the citation to demonstrate correct opacity levels or you could receive an $1800 penalty. Even worse, the vehicle could be taken out of service.

Call Diamond Service today at 408-263-7300 for affordable San Jose, Bay Area, and California opacity testing and repair quotes.
Mitsubishi Fuso Authorized Dealer

Hours of Operation:

Mon – Fri: 8:00AM – 5:00PM

Weekends or After Hours by Appointment

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Diamond Mitsubishi Fuso

1505 N 4th St. San Jose, CA 95112

(408) 263-7300


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