Car Maintenance And Repairs

How Many Miles To Reset Computer On Car?

Mike Cross
Updated Jul 3, 2021
How Many Miles To Reset Computer On Car

So, you need your car’s computer to reset and it won’t. You have been driving it for what feels like a bunch of miles, but it still won’t reset. What can you do about this?

Well, read on in this article to find out exactly what you have to do to get your car’s computer to reset.

After reading this article you will have a better idea of how many miles you will need to drive your car to get the computer to reset, but more importantly, you will know the conditions required to get your car’s computer monitoring to reset.

Why do you need it to reset?

So, some of you may be wondering why you might need your computer to reset. Well, there are two possible reasons why you might want this to happen.

The first is a common reason, and that is that you are trying to get your car to pass carbon inspection. In order to pass your car has to run certain checks and not put off any codes.

How Many Miles To Reset Computer On Car
How Many Miles To Reset Computer On Car

If you went to the testing place and they connected their scanner and told you that you failed because the computer hasn’t reset, then that might be why you are here now wondering how far you have to drive your vehicle to get the computer to scan all the systems.

The other reason why you might want to get the computer to reset is that you had a code trigger or you had a mechanic tell you something was bad on your car and you want to make sure that is actually the case before having something replaced or fixed.

Sometimes your car can throw codes out of the blue and for no reason, so if it isn’t something major you can reset and clear the code and then see if the computer sends the same code again.

If it does, then that means the part related to the code probably is bad, but if you have been driving for a while and the computer has done the checks, and it doesn’t resend the code, then you know you don’t need that part replaced.

How far to drive?

So, for passing emission test how far do you have to drive before it is ready to pass the test. Well, the answer is it depends. It all depends on how you are driving the car because certain conditions have to be met for the car’s computer to run the check on the different sensors.

For some people, it is ready to go after about 50 miles, but for others, they have to drive much farther upwards of a couple of hundred miles sometimes. This is because the system has to make sure the vehicle is safe thru a variety of readiness monitors.

Depending on the make and model of your vehicle it could have to perform up to eleven different readiness monitors to make sure all the sensors are working right and that the emissions are correct.

How to know if ready?

So, how can you know that your car is ready before taking it to get tested? Well, to do this you have to have an OBD2 scanner and plug it into the OBD2 port normally below the steering wheel.

You then go to the emission output section, and it will read with one of three outcomes. “Ready” which means that the car has run the required readiness monitors and that you can pass the emission test, “not ready” which means the car still hasn’t run the required test or “not applicable” meaning your vehicle doesn’t have self-monitoring system.

OBD2 scanner
You have to have an OBD2 scanner know that your car is ready before taking it to get tested

How to Get Car to Check Itself

So, how do you get the car to run the readiness monitors if it is in the “not ready” mode? Well, most people think that that means you have to drive the car a bunch, but that is actually not the case.

It is actually about the conditions that the car is driven in that triggers the monitors. To get the OBD2 drive cycle to begin, you must start with a cold start. That means if your car didn’t cool down below a certain threshold from your last trip, then it won’t do a check.

The coolant temperature must be below 122 degrees Fahrenheit, and the air temperature sensor must be within 12 degrees of the coolant to get an OBD2 drive cycle to start.

If that requirement is met, then the ignition must not have been left on before the cold start because this may cause the oxygen sensor not to check.

If he is also meet, then the next thing to do is to let the car idle for two and a half minutes with the air conditioner, and rear defrosts turn on.

After the two and a half minutes have passed, you can turn the AC off and rear defrost off and then accelerate the car to 55 miles per hour. You want to make sure to accelerate under moderate constant acceleration and then let the car cruise at 55 miles per hour for three minutes.

After the three minutes have passed you want to begin slowing down, but you don’t want to use the brake or clutch if in a manual.

Instead, you just want to coast and slow down naturally until you are down to 20 miles per hour. Once you reach this point, it is time to accelerate smoothly back up to 55 to 60 miles per hour. Once at that speed cruise for another five minutes.

Then you can begin to decelerate again without braking or clutching and come to a complete stop. This is full should count and trigger as a full drive cycle for your vehicle.

When your car running in long time, you should have best battery tender for car to recharge your battery, it's important things, your car won't start if battery is dead or low battery.

How many drive cycles?

So, how many drive cycles do you have to do before your car resets? Well, with most cars you need about three drive cycles to be done.

If you really need to pass the test soon, then you can do short drives like this all in a row once the car has cooled down enough, but you need to make sure to wait at least a few hours between drives to make sure the car is cool enough.

If you are trying to reset the computer to see if a part is bad, then you really don’t need to worry about forcing the car’s computer to run a check. If the part is bad, it will trigger the light quickly enough, and if it isn’t bad, then the check engine light won’t come back on.

Normal driving will allow for a drive cycle to occur, but it is important to remember that when it comes to getting your vehicle’s computer to reset it isn’t how far you drove it, but instead the conditions you drove it in.


Getting your car’s computer to reset is an important thing, especially if you really need to pass your emission test. That is why it is good that you now know how your car checks the different emission parts and uses a drive cycle that tests all the sensors during a drive.

You know that to get a drive cycle to activate you have to have a cold start and then accelerate and decelerate a few times before stopping and turning the vehicle off.

Also, you now know that there is no magic distance to drive to get your computer to reset. For some people, they can get the required number of drive cycle in as little as 50 miles while others may drive a few hundred before getting the drive cycles conditions met.

Now you know to the secret to getting your car’s computer to reset so you can pass an emission test and not get the “not ready” indicator the next time you go for emission test. You also know how to check it yourself with an OBD2 scanner to make sure your car is ready to pass before going to get the emission test.

Mike Cross
Life is too short to drive with stock audio

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4 comments on “How Many Miles To Reset Computer On Car?”

  1. Thank you for a clear description of resetting a car's computer for passing emmisions tests. This makes more sense to me than just driving miles and miles of no exact amount just to pass. Now I understand and can focus on doing the right thing to move forward QUICKLY and efficiently to pass the test. I wish I known this before I ran out of time to pass the test. Now I have to drive with expired tags because my car STILL needs to reset as time ran out for me (forgot to have it tested because I wasnt driving due to Covid quarantining and I eventually recieved a final noticen and they won't give me an extention). Or be forced to purchase a different vehicle to avoid the possibility of getting a ticket for expired registration is an option, albiet a ridiculous and expensive one.
    Wish I had found your article sooner before being placed between a rock and hard place with a perfectly running newer vehicle.

  2. The bottom line is that the emissions tests are 80 gallons of excrement in a 50 gallon drum.

    Relying on such nonsense. Test the emissions on-site, don't rely on computers and ECU's that are unpredictable, finicky and squirrely.

    Better yet, they can stick their "emissions" tests the same place they can stick the rest of their bureaucratic rackets.

    More of the hypocrisy and incompetence from our worse-than-worthless "public servants."


  3. Q7, 2011, TDK, not so many miles, about 79K, and yet, it simply cannot be smogged. what started this mess, was in November, got an oil change and add-blue service. Big mistake, because the check engine light came on. I was not that worried, because the registration and smog were not late until Feb. 1st. Wrong. the same general cycle has been repeated 4 times now, since November. take it to the dealer. they do some minor repair, three times it was replacing censor monitors that were a recall issue, so they have been free. BUT, each time I am told to drive it 150-200 miles so the 'monitors can re-set'. Only problem is, usually the check engine light comes back on before that milestone. Since this happened twice--driving it about 3 weeks but the check engine coming back on, this last time, I thought I would only go 1 1/2 weeks, don't push my luck, if the check engine light is off, just go to the smog place again. I even go in the morning and run the engine for 25 min. before the test. not good enough, fail again. this time it said the catalytic converter monitor. Stupid Audi. Costs so much, yet how does anyone bear this irritating problem? (that I have never had with American or Japanese cars since I began driving in 1978.

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