101 Express Smog


Why Choose Us?

Our goal is to take the hassle out of the process by providing quick and honest smog testing at our Petaluma location.

DMV Registration Services

As a licensee of the DMV, we offer registration renewal, title transfers, and out-of-state registration services

Double Capacity = FAST

We have 2 smog machines for even shorter wait times for our customers.

$10 Off Coupon

For a limited time we’re offering a $10 off coupon to help you save and get the best price in the area on your smog.

Our Services

View our services offered and book an appointment online.

Smog Test

We offer fast smog testing services to all vehicles requiring a smog certificate. From your everyday driver to your one-of-kind collector car, your vehicle will be in good hands with our friendly and experienced techs. Whether you drive a passenger car or medium sized truck or SUV, our mechanics strive to ensure that your vehicle will be performing at its best.

DMV Registration

We are a licensee of the Department of Motor Vehicles in California and can provide the same services as your local DMV office – without waiting for hours in line! We are also open on weekends for your convenience. Services include:

  • Vehicle Registration Renewals
  • Used Car Transfers
  • Transfer of Ownership
  • Out-Of-State Registration
  • Duplicate Title
  • Lost Registration or Stickers replacement
  • Lost Title Notarization

Save with us

Download and present this coupon when you visit to save $10 on your first smog test

Book an Appointment

When filling out the form, include your vehicle make, model, and year in the “Appointment Notes” field. 

For same-day appointments, please give us a call at (707) 664-9600. Please call for vehicles model year 1999 and older, as well as motorhomes. These take extra time and we want to make sure we leave enough time for these vehicles! 


Review our FAQs below and feel free to reach out if you still have questions for us!

We have a variety of scheduling options to suit your needs:

  • Use our on-line appointment system, or for same-day service, give us a call and we can “hold a spot” for you. (707) 664-9600
  • Drop in anytime and relax at any of the restaurants or cafes in the plaza
  • If you are in a hurry and just want to drop your car off, you can fill out a short form and be on your way fast, even when we’re busy. We’ll call you when it’s ready


Yes, we do! The result of your test is electronically transmitted to the DMV’s computer when your test is completed. You will also receive a signed and dated copy for your own personal records.

As you drive your car, its on-board computer runs a series of up to 11 tests. These tests, known as “monitors,” check your car’s various components and systems and the results determine whether or not your car’s “check engine” light is turned on.

As the monitors run, their status changes from “not ready” (or “incomplete”) to “ready” (or “complete”). All of the monitors will be set to “not ready” if your battery is disconnected or your computer is reset with a scan tool.

Part of the smog inspection includes checking the “readiness” of the monitors and if more than the allowed number are not complete, your car will not pass, and the test will show “not ready”.
Normally, driving your car for a few days will resolve the problem, but if it does not, other problems may exist that require further diagnosis from a qualified repair shop. It is also possible that your car’s monitors are inherently difficult to set. The Bureau of Automotive Repair (BAR) has a published list of these vehicles it has identified, and we are happy to help you determine if any of them apply to your vehicle.

In some circumstances, exemptions apply to readiness requirements, and we will be happy to explain them if you have any questions regarding your vehicle.

If your car does not pass, the problem should be diagnosed and repaired, and when you bring it back to us, your retest is discounted!

Here are some suggestions you might find helpful:

  • Assistance is available from the State. Information and application forms are available in our lobby. It is important that you review these options before seeking repairs if you wish to receive assistance.
  • Give the repair station a copy of the Vehicle Inspection Report (VIR) you received from us. Let them know that we are happy to answer any questions they have.
  • Explain to them that your car failed its smog inspection, and you want it repaired so that it will pass. Have them write this on your estimate.
  • When you pick up your car after the repair, ask them if it is ready for inspection.

Some vehicles require a Smog Check at a STAR station. STAR stations must meet specified performance standards established by BAR. Some STAR stations (like 101 Express) are licensed to perform solely tests, while others are licensed to perform both tests and repairs. The station is required to post a sign on the services it performs. The STAR sign is bright red and can usually be found hanging directly under or near the station’s Smog Check sign.

Another great question! State law requires testing a percentage of the vehicle fleet at STAR-certified stations. These vehicles are known as “directed” vehicles. Some are simply selected at random, and while the exact selection criteria is not defined, the State offers the following explanation:

Model-year 1999 and older vehicles must have their inspections performed at a STAR station. These vehicles still require a tailpipe inspection of emissions. STAR stations are required to have this equipment.

In addition, model-year 2000 and newer vehicles with the greatest likelihood of failing their next inspection are directed to STAR stations. Smog Check history of vehicle groups (e.g., model-year, make, model, body style, engine displacement, and transmission type) is a major factor in this directed vehicle selection process.

The first six model-years do not require biennial inspection, and therefore are not included in the Directed Vehicle Selection Methodology.

If you bring us the car, we can inspect it! Your renewal notice (the one with the large barcode across the top) will expedite your visit, but is not required.

Contact 101 Express Smog

For same-day appointments, please give us a call. For all other questions and inquiries, contact us directly via the form below.