Understanding the Drive Cycle After a Repair

Nancy breaks down how a drive cycle works to get your car monitors back to normal after your vehicle was repaired.


Wow. Time goes by so quickly and your vehicle is due for a New Jersey State Inspection again, but your check engine light’s on.

Hi, I’m Nancy at Kneble’s Auto Service Center. Now I know you’ve heard it time and again that that vehicle will fail with a check engine light on so this time you get smart and you have your vehicle repaired before the inspection. Now once has repaired, your technician now tells you that a drive cycle needs to be done to get the monitors ready for inspection. So you think, “Nah, that won’t take long, that should be easy. They just need to drive the vehicle around the block and inspect it.” Well, vehicles are designed with a power train control module, a PCM. It monitors the vehicle’s emission system which refers to the number of pollutants that are emitted in the air, so understand there are eight components of the system and if any of them fail the parameters that check engine light will go on.

To pass New Jersey State Inspection, seven of the eight monitors need to be read by the vehicle’s system and show ready. Now, this is where the drive cycle comes into play. A drive cycle isn’t just that quick drive around the block you think. It is designed to simulate a typical driver using their vehicle first thing in the morning after sitting overnight when the engine is cold. The vehicle is driven at a low speed of 25 to 35 miles an hour while doing frequent stops like you’re traveling on city streets. Then it is driven steady at a highway speed of 55 to 60 miles an hour for about four to five miles. Then it reverts back to that city speed of 25 to 35 miles an hour for a little bit longer than it idles for 20 to 30 seconds where it’s finally turned off. That’s a lot of specific driving.

Now sometimes this process may take several more drive cycles before the monitors show ready for inspection, so it’s not uncommon for drive cycles to be done over several days before the PCM reads all the monitors for that inspection to occur. Wow. Because it’s such specific driving, and it may take a while, we may recommend the customer picking up the vehicle after the repair, and for them to use their vehicle over several days, and then bring it back to us to have it scan their PCM to determine if the vehicle’s monitors are read and that they’re ready for inspection.
Thank you for watching and remember, check out a new video every Wednesday at 12:30. Thank you.