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Understanding Smog Test Says "Not Ready"

  • remicaubert
  • May 29
  • 5 min read

Updated: Jul 13

What Does Smog Test Says "Not Ready" Mean?


Your vehicle’s onboard computer runs self-tests on various emissions systems. It checks that each relevant monitor, like the oxygen sensor and evaporation system, is complete. This means it has enough data to give an accurate measurement.


When your car shows "Not Ready," it means the vehicle’s computer system can't finish running all the tests it needs to pass the smog test. There isn't enough data!


"Not Ready" is different from failing the smog test. Your vehicle may pass once the monitors are complete.


Why Does This Happen?


There are a few reasons your car smog test says "Not Ready":


  • You or your repair shop recently cleared the car’s computer codes. This resets the computer monitors to zero.

  • The vehicle has been sitting in a garage.

  • The car hasn’t been driven enough, or in the right way, to complete the tests. This often happens when you mostly drive short distances, like city driving.

  • There might be a problem with the emissions system that stops the monitors from finishing.


The first three reasons are the most common. You would be surprised how often it happens. No need to worry.


How to Get Your Vehicle Ready for the Smog Test


If your test says "Not Ready," don’t rush to your repair shop or dealership right away. First, you need to drive your car in a way that enables the computer to complete its data and tests. This is called a "drive cycle."


What Is a Drive Cycle?


A drive cycle is a set of driving conditions that help your car’s computer check all the emissions systems. It usually means driving at different speeds, idling, and sometimes stopping and starting.


Here’s a simple example of a drive cycle we recommend:


  • Start your car and let it idle for about 2 minutes.

  • Drive at a steady speed of 40 to 60 mph for 10 to 15 minutes. For vehicles used to driving short distances, we typically recommend driving 60 miles at 60 mph on the freeway.

  • Include some stops and starts during your drive.

  • Avoid turning off the engine during this time.


This helps the car’s computer complete all the tests it needs. After this, the "Not Ready" message should clear, meaning all needed monitors are complete. Ask your favorite technician to scan your vehicle's computer to check this before they run the test again. You may still need to drive it more.


Please note that all vehicles are not created equal! Some models need more miles to complete all monitors. Trust your technician when they ask you to drive it more. It's for your own good. It's cheaper than having it done by the dealership. Most times, a repair is not necessary!


When to Get Help


If you’ve completed the drive cycle and brought the vehicle to us several times, and your car still says "Not Ready," it might mean there is a real problem. Some parts of the emissions system might not be working right. Your smog technician will recommend checking with your usual repair shop.


check engine light stays on - smog check says "not ready"

Smog Check Service at Smog Express


Whether you live in San Pablo or Hercules, you need a smog check station you can trust. Smog Express in Richmond has been serving the East Bay for over 30 years. With a high satisfaction rate of 4.8 stars and over 700 Google reviews, we are here to help and make the process easy. Our ace techs know how to handle "Not Ready" vehicles.


We are Star Certified by the Bureau of Automotive Repair. We also offer one free retest with your first quote. This enables you to drive the vehicle, get it ready, and pay for the service only once. We are a smog test-only facility. We do not get involved in pricey repairs. Trust us to help you solve this "Not Ready" issue.


You can learn more about our smart tips here: Smart Tips.


Emissions System Repair


If your car has a real emissions problem, you might need repairs. Common fixes include replacing oxygen sensors, a faulty valve, the catalytic converter, or fixing leaks in the exhaust system.


Vehicle Health Monitoring Tools


There are tools you can use at home to check your car’s emissions system. For example, an OBD-II scanner can read your car’s computer codes. This helps you see if there are any issues before going to the smog check. You can find many affordable OBD-II scanners online or at auto parts stores.


Tips to Avoid "Not Ready" in the Future


To keep your car ready for smog tests, follow these tips:


  • Avoid disconnecting your car battery unless necessary or letting it die.

  • Drive your car regularly and include highway driving.

  • Fix any check engine light issues quickly.

  • Use quality fuel and keep up with regular maintenance.


These simple steps help your car’s computer run its tests and keep emissions low.


Dashboard showing the check engine light still on although the engine is running, a sign to check the emissions system.


What to Do If You Fail the Smog Test


If your car fails the smog test, don’t panic. First, ask for a detailed report. It will tell you which part of the emissions system caused the failure.


Next, get a trusted mechanic to inspect your car. Fixing the problem usually means replacing or repairing parts like sensors.


After repairs, you can return for a retest. A station like Smog Express offers a free retest or can guide you through the process.


Why Choose a Star Certified Smog Check Station?


Star Certified stations meet strict standards set by the state. They have the right tools and training to handle all smog check issues, including "Not Ready" vehicles.


Choosing a Star Certified station means you get accurate results and expert advice. Smog Express is proud to be a trusted Star Certified smog check station in Richmond and the East Bay. We make the process simple and stress-free.


Final Thoughts


Seeing "Not Ready" on your smog test can feel like a setback. But it’s not the end. Most of the time, it means your car’s computer just needs more time or the right drive cycle to finish its tests.


If you follow the right steps, you can get your vehicle ready. Use drive cycles, check for issues, and get help from trusted places like Smog Express.


Remember, keeping your car well-maintained helps avoid "Not Ready" and makes smog checks easier. Take care of your vehicle, and the smog test will be just another quick stop.


Ready to get your smog check done right? Visit Smog Express for fast, friendly, and reliable service in Richmond and the East Bay. Your car will thank you.

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