Resetting the check engine light is a common task for many drivers. The check engine light can turn on for minor issues like a loose gas cap or for more serious problems like faulty oxygen sensors. Once the underlying problem is fixed, the check engine light needs to be reset so it will turn off and stay off.
How Long to Drive After Resetting Check Engine Light
After resetting a check engine light, many drivers wonder how long and far they should drive in order for the check engine light reset procedure to complete. Here are some general guidelines:
- Drive at least 10 to 15 miles after resetting the check engine light. This allows various monitors on the vehicle’s computer to run their diagnostic testing and complete their drive cycle.
- Avoid stopping and starting the engine during this drive. Continuous driving allows the diagnostic testing to finish.
- Highway driving or 15 minutes of steady driving is ideal for allowing the reset procedure to complete.
- Don’t turn off the engine until the minimum miles/time has elapsed.
- The check engine light may take three drive cycles to reset, so a second drive may be required if it comes back on.
These guidelines help ensure the diagnostic monitors have finished their testing needed to verify the repair was completed properly and keep the check engine light off. However, every vehicle and situation can be different, so refer to your vehicle repair manual for exact procedures.
Common Causes of Check Engine Light
There are many issues that can trigger the check engine light to turn on. Here are some of the most common causes:
- Loose or faulty gas cap – A loose gas cap allows fuel vapors to escape, which sets off an evaporative emissions code.
- Oxygen sensor problems – The oxygen sensors monitor the air-fuel ratio. Faulty sensors will cause emissions problems.
- Catalytic converter failure – The catalytic converter controls emissions. A damaged converter can’t properly reduce pollutants.
- Spark plug issues – Faulty or fouled spark plugs lead to ignition problems and high emissions.
- Mass airflow sensor problems – The mass airflow sensor calculates the proper air-fuel mix. A faulty sensor disrupts engine performance.
There are hundreds of different trouble codes that can turn the check engine light on. To diagnose the underlying problem, the trouble codes must be retrieved from the vehicle’s computer using a code scanner. This helps identify the specific components or systems affected.
Is It Safe to Drive With Check Engine Light On?
The check engine light turning on does not necessarily mean you have to immediately pull off the road. However, it does indicate there is some problem with an engine management component or the emissions system.
Here are some guidelines for whether it is safe to drive with the check engine light illuminated:
- If the vehicle is running normally, you can likely drive home or to the repair shop safely. However, the problem should be diagnosed as soon as possible.
- If the vehicle is running poorly, has no power, stalls, etc., it is not safe to drive. These symptoms indicate a serious problem like ignition failure or a bad sensor.
- Never ignore the check engine light. Even minor code issues can lead to more serious problems if left untreated.
- Blinking or flashing check engine lights indicate an urgent problem, like engine misfire or catalyst damage. Stop driving and repair immediately.
The check engine light is designed as an early indicator of emissions-related issues to prevent excessive emissions and damage. Ignoring the light could lead to expensive repairs down the road.
Can Check Engine Light Reset Itself?
Some minor issues may cause the check engine light to turn itself off after a few drive cycles. Here are some examples of codes that may go away on their own:
- Loose gas cap – After retightening the gas cap for a few drive cycles, the caps sensor will reset and turn off the check engine light.
- Temporary sensor glitches – A glitch with the mass airflow or oxygen sensors may trigger a code but not reoccur during subsequent drive cycles.
- Issues caused by bad fuel – Contaminated or bad fuel can trip many engine management codes but go away once filled with good fuel.
However, the check engine light turning off on its own does not mean the problem is fully resolved. The underlying condition that caused the code may still be present or intermittent. It is best to still have the vehicle serviced so a technician can check for the root cause.
How to Reset Check Engine Light
Once you have diagnosed and repaired the issue causing the check engine light, you’ll need to reset the light so it will turn off. Here are the steps for resetting a check engine light:
- Fix the underlying problem first. Don’t just reset the light without addressing the issue.
- Locate the check engine light reset procedure for your vehicle make and model. This can usually be found in the owners manual or repair manual.
- Turn the ignition key to the “ON” position without starting the engine.
- Based on your vehicle, either:
- Press and release the gas pedal 3 times within 5 seconds
- Turn the ignition key to OFF, then to ON 3 times
- Press a reset button on dashboard or scanner tool if equipped
- The check engine light will turn off once the reset procedure is complete.
- Verify the light stayed off after a short test drive.
Consult an auto parts store or mechanic if you’re unsure of how to reset the check engine light for your vehicle make and model. Many auto parts stores will reset the light for free with a code scanner.
Can a Check Engine Light Reset Tool Work?
There are many handheld code scanner tools available that claim to reset check engine lights. Do these scanners work to reset lights?
- Yes, scanner tools from quality brands do work to reset check engine lights. They connect to a vehicle’s computer and can erase stored trouble codes.
- Scanner tools provide an easy “one-click” method to reset the check engine light. However, they only erase the code and turn the light off.
- The check engine light will simply re-illuminate if the root cause was not yet fixed. Resetting without repairs will only mask an issue temporarily.
- Code scanners are useful diagnostic tools and make resetting convenience. But repairs should always be made first before resetting the check engine light.
So in summary, yes check engine light scanners can turn the light off but are not a miracle cure-all. Proper repairs to coded issues must still be performed first.
Should You Replace Car Because of Check Engine Light?
Illuminations of the check engine light do not necessarily mean you need to replace your vehicle entirely. Here is some guidance on when to repair vs. replace a vehicle due to check engine light issues:
- If repairs are affordable (e.g. $200-500), repairing is likely the better option over replacing the vehicle.
- However, if a major engine component has failed like the catalytic converter or computer module, replacement costs of $1,000+ may make sense to replace the vehicle.
- Weigh the costs of upcoming repairs versus the current value of your vehicle. Repairs exceeding the vehicle value favors replacement.
- Consider the vehicle’s overall condition, maintenance history, and longevity when deciding between repairing or replacing.
- Minor check engine light issues like oxygen sensor codes do not require replacing the vehicle.
The check engine light does not automatically mean the vehicle is ready for the junkyard. Consider the severity, overall costs, and longevity factors when determining if repairs or vehicle replacement is the right choice.
Frequently Asked Questions
How long does it take for check engine light to reset?
It typically takes 10-15 miles of driving for the check engine light reset procedure to complete after repairing the underlying problem. Some vehicles require up to 3 drive cycles for monitors to run and reset the light. Always check your vehicle repair manual for the specific reset procedure.
Will check engine light reset itself?
The check engine light can reset itself in cases of minor issues like a loose gas cap. But the light turning off on its own does not mean the problem was fully resolved. It is still best to have a technician diagnose any code that appeared.
Can you pass emissions with check engine light on?
Most vehicles will not pass an emissions test if the check engine light is on. This indicates an emissions-related fault is detected. The vehicle will need to be repaired and have the light reset in order to pass an emissions inspection.
How do you reset check engine light without scanner?
The check engine light can be reset without a scanner by turning the ignition on and off in a specific sequence. The steps vary by vehicle make and model. Consult a vehicle repair manual for the specific procedure. Auto parts stores can also reset the light for free with a scanner.
Why does my check engine light keep coming on?
If the check engine light keeps illuminating, the underlying problem was not properly diagnosed and repaired. The same code keeps triggering because the root cause was not addressed. You will need to fully diagnose
and resolve the issue before resetting the light again.
