Last Updated: 08/06/2022 @ 07:48 am

Credit: floydthedog

You really need an OBD II code reader/eraser to tackle this problem. I got mine a few years ago from Autozone for like $120, and I can’t even tell you how valuable it has been.

THIS IS HOW I PASSED MY SMOG CHECK – vs. a never-ending code 1320!

You will need:

  • OBD tool
  • Printout of System Readiness Drive Pattern for your model (yes it is silly)
  • Access to a freeway that is not too busy (you will be traveling slower than normal traffic and trying to hold maintained speeds)
  • You should also try and do this starting with a little less than 1/2 tank of fuel.

** I’ve found that the best freeway system to do this will have 6-8 continuous miles of flat or upwards sloping hills, followed by a downslope. In or around Los Angeles, you can get on the 5 south at Magic Mountain and by the time you reach the top of the hill, it’s the perfect time to downshift and coast.**

Abbreviated Systems reset procedure. (At least for my car!)

  1. Get your car close to your freeway on-ramp. (make sure it is warmed-up)
  2. Reset CEL
  3. Start car and let idle for 1.5 minutes – leave A/C off for now
  4. Get on the freeway, get up to 4th gear and try and hold the RPMs just over 3000 (3100 should be fine) you should be traveling around 60-63 MPH. HOLD THIS STEADY FOR 3 MINUTES>
  5. Shift into 5th, steady speed around 56 MPH, turn A/C on, set cruise control, HOLD FOR 3 MINUTES.
    At this point, you should be getting close to the top of the hill, wait until you crest the top, then…
  6. Downshift into 4th, take your foot off the gas and just let it go for 5-6 seconds, then drop out of gear and let it coast for 1 minute without braking for as long as possible.
    At this point, 4 of my 5 systems that need to come back online had reset. (I’ve successfully done this on 3 separate occasions.) If you leave your OBD tool hooked up while driving you can check the status by looking at the I/M Indicators. The 5 that we’re looking for are O2 Heater, EGR, Catalyst, O2 Sensor, and EVAP.
  7. Get off the freeway and go to the first smog check place you can find. (probably helpful if you plan that out beforehand)

In California, my understanding is that you can take the smog test with a maximum of 2 system readiness indicators not ready, but no more than that.

So the plan here is to get at least 3 of your 5 SR indicators back online, then get the smog check before the CEL comes back on. You don’t have much of a window to do this, and I would recommend limiting turning off and restarting the car as much as possible. I’ve even let it idle in the front of the Smog place while I went and checked in.

Out of the 3 times, I have done this the CEL has always come back within 10 miles of leaving the Smog Check, 2 years ago, it came on as I was pulling out of the lot. Luckily, I had just passed my test. But I have always had a small window to get it done before the light comes back. It’s actually pretty nerve-wracking sitting in the smog check place praying the damn light doesn’t go on during the test. But if you pass, it’s completely worth it. I feel like framing my last pass certificate.


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