In a car, "10 to 20 cycles" refers to a specific number of instances where you turn the car on and then turn it off again. This sequence, from ignition to shutdown, constitutes one "cycle."
These 10 to 20 cycles are particularly significant because they often represent the period required for a car's internal computer to complete a full system check and potentially reset certain diagnostics or error codes.
Understanding Car Cycles
A "cycle" in the context of a car's onboard diagnostics is a simple yet crucial concept:
- One Cycle: The action of starting your car's engine and then shutting it down.
The Significance of 10 to 20 Cycles
The range of 10 to 20 cycles is often cited as the period during which a car's internal computer performs a thorough re-evaluation of its sensors and systems. This process is vital for the automatic clearing of certain diagnostic trouble codes (DTCs), such as those that trigger a Check Engine Light (CEL), after a repair has been performed.
Here's why these cycles are important:
- Computer Reset: Your car's onboard computer (often referred to as the Engine Control Unit or ECU) continuously monitors various sensors and components. After a repair, especially one related to an engine light, the computer needs to verify that the issue is resolved. This verification often occurs automatically after a set number of cycles.
- Sensor Re-evaluation: During these cycles, the computer checks all its sensors once more to ensure everything is operating within normal parameters. If the previously detected fault is no longer present, the computer can then clear the error code and turn off the corresponding warning light.
Cycle-Based vs. Mileage-Based Resets
While many cars rely on these start-up/shut-down cycles for their computer to reset and re-check systems, some vehicles, particularly older or specific models, might require a certain amount of driving distance before their systems fully reset. For instance, some vehicles may need to be driven anywhere from 50 to 100 miles for a complete reset of certain parameters. However, for many modern cars, the cycle-based approach is common for resetting the internal computer after sensor checks.
Practical Application
Understanding "10 to 20 cycles" can be highly practical, especially if you've recently had a repair that caused a dashboard warning light, like the Check Engine Light, to illuminate.
- Post-Repair Verification: After a mechanic fixes an issue, the Check Engine Light may not turn off immediately. Driving your car through 10 to 20 full cycles (turning it on and off) can give the car's computer enough time to confirm the repair and clear the code automatically.
- Diagnostic Readiness: These cycles are also part of what are known as "drive cycles" or "readiness monitors." These are specific driving conditions and sequences required by the ECU to run all its diagnostic tests. All monitors must complete their tests for the vehicle to be considered "ready" for an emissions inspection.
How to Complete a Cycle
Completing a cycle is straightforward:
- Start your car: Turn the ignition key or press the start button to power on the engine.
- Drive (optional but recommended): Drive the car for a short period, allowing it to reach operating temperature. This is often necessary for some diagnostic monitors to run.
- Turn off your car: Shut down the engine completely.
Repeating this sequence 10 to 20 times will help the car's internal computer complete its necessary diagnostic checks and reset procedures.
For more detailed information on car computer diagnostics and drive cycles, you can refer to resources on automotive diagnostic procedures.
