A drive cycle is a series of driving maneuvers and conditions that allow the vehicle’s onboard diagnostic system to perform self-checks on various components and systems.
These checks help in verifying that everything is functioning correctly and that any previously identified issues have been resolved.
Completing a drive cycle is important to be sure your car is running efficiently and ready for the emissions test. So, how do you tell if the drive cycle is complete?
How to Tell If Drive Cycle is Complete
Here’s how to know if a drive cycle is complete:
1. No Check Engine Light
If your check engine light was on before you started the drive cycle, once you complete the drive cycle, the check engine light will turn off from your dashboard, indicating that the cycle is complete and you’re car is running efficiently with no fault codes.
However, if the check engine light is still on, the drive cycle is not complete, or there might be a problem that needs addressing.
Also, if the CELL light was off before you started the drive cycle and turned back on during the drive cycle, it means a problem has been detected, and the cycle will not be completed until the issue is resolved.
2. Using OBD-II Readiness Monitors
Another way to tell if the drive cycle is complete is by using the OBD-II readiness monitors. You can use the OBD-II scanner to check the status of the readiness monitors.
The scanner can tell you if the monitors are set to “ready” or “not ready” by checking the following monitors:
- Misfire
- Fuel System
- Comprehensive Components
- Catalytic converter
- Heated Catalyst (if equipped)
- Evaporative System
- Secondary Air System (if equipped)
- Oxygen Sensor
- Oxygen Sensor Heater
- EGR System (if equipped)
As reiterated earlier, once a drive cycle is completed, all non-continuous monitors should transition from “not ready” to “ready.”
3. By Completing Your Vehicle-Specific Drive Cycle Procedures
Some cars have their specific drive cycle procedure, if you complete the procedure as directed by your car manufacturer, and there is no CELL light afterward, the drive cycle must be complete.
To know this procedure, you can check your car’s manual. However, the general drive-cycle procedure for almost all cars is as follows:
- Let the vehicle sit for at least 8 hours without starting.
- Start the engine and idle for 2-3 minutes, with the air conditioner and rear defroster on.
- Turn off all accessories and let the vehicle idle for another 2-3 minutes.
- Make sure the coolant temperature is close to the ambient temperature.
- Drive at a steady speed of about 20 – 30 mph for 2 – 3 minutes.
- Accelerate to a speed of 55 mph and maintain it for 5 – 10 minutes. Use the cruise control if possible.
- Slowly reduce speed to 20 mph without using the brakes, then gently accelerate back to 55 mph and maintain for 5 minutes. Include some stop-and-go conditions with varied speeds.
- Bring the vehicle to a stop and let it idle for a few minutes.
Once you followed this procedure and the check engine light or no other warning light comes on on your dashboard, you must have completed the drive cycle.
4. If You’ve Driven for a Long Time
Completing a drive cycle involves driving for long hours and sometimes days. However, the length can vary depending on the vehicle’s make and model.
Therefore, a complete drive cycle can take anywhere from 30 minutes to an hour or even days and it involves a combination of idling, city driving, and highway/expressway driving. It all depends on how you drive and how long you’ve driven the car since started the test.
5. No Pending Codes
Once a drive cycle is complete, there should be no pending codes on your car’s computer. This is because a successful drive cycle will clear all pending codes, meaning the system has not detected any faults during the cycle.
You can use an OBD-II scanner to check for any pending diagnostic trouble codes. As long as you find no codes in the system, you’re good to go.
Be that as it may, to be able to perform a successful drive cycle and get a complete result, you must begin the drive cycle with a cold engine, meaning the engine and ambient temperatures should be similar, and the vehicle has not been driven for several hours (8 hours).
This is to ensure that the OBD-II system can perform accurate tests from a cold start, which is necessary for certain monitors. Also, you need to make sure the gas tank is between 1/4 and 3/4 full before starting the test.
How Many Miles is a Drive Cycle?
A drive cycle requires driving 10 to 20 miles under various conditions to complete.
Why Won’t My Car Complete a Drive Cycle?
There are several reasons why your car might not complete a drive cycle. They are:
- Incomplete or Incorrect Procedure: Not following the steps and conditions required for the drive cycle can prevent it from completing.
- Pending Diagnostic Trouble Codes: Active or pending trouble codes can halt the completion of the drive cycle. You can use an OBD-II scanner to check and clear any codes.
- Unresolved Mechanical Issues: Faulty components such as oxygen sensors, the catalytic converter, or the EVAP system can disrupt the drive cycle.
- Improper Operating Conditions: The drive cycle may require specific conditions like a cold start or a particular fuel level usually between 30% and 70%).
- Battery Disconnection: Disconnecting the battery can reset the OBD-II system, requiring the drive cycle to be restarted.
- Short Trips: Frequent short trips without allowing the engine to reach operating temperature can prevent the drive cycle from completing.
- Software Glitches: Sometimes, the vehicle’s onboard computer might need a software update to correctly complete the drive cycle.
- Environmental Factors: Extreme temperatures or altitude can affect the vehicle’s ability to complete the drive cycle.
Conclusion
Since completing a drive cycle is important to ensure your car is running efficiently and ready for an emissions test, you should know when the drive cycle is complete.
Once the check engine warning light does not come back on and no pending codes on your car’s computer, it indicates the drive cycle is complete.
However, you need to use an OBD-II scanner to check the status of the readiness monitors. The scanner should indicate if the monitors are set to “ready” or “not ready.”
If all monitors are “ready,” the drive cycle is complete. If some monitors are still “not ready,” you may need to repeat the drive cycle or fix any issues indicated by the Check Engine Light.
