Seeing the check engine light come on can be stressful, but it doesn’t always mean disaster. The key is knowing how to respond in the moment, how to do a few smart checks, and when to stop driving and get help.
Always pay attention to the instrument panel
As you drive, quickly scan what the car is telling you. Don’t just focus on the speedometer or your gas gauge. Look at the other gauges, and for warning lights. If you see alerts for low oil pressure, high coolant temperature, or a charging system issue, pull over as soon as it’s possible and turn off the engine. Continuing to drive with these warnings can cause serious damage.
Furthermore, if the engine is shaking, misfiring, lacking power, or making noises, slow down and head for a safe place to stop. As you do, avoid hard acceleration and high speeds.
What steady vs. flashing lights tell you
Not all check engine lights mean the same thing. For instance, a steady (solid) check engine light usually points to an emissions or drivability issue that isn’t immediately catastrophic. In many cases, you can drive to a nearby mechanic or your home. Just be mindful of the temperature gauge; if the needle begins to rise, you’ll want to stop operating the vehicle ASAP.
If you see a flashing check engine light, treat it as an emergency, as it typically signals a severe misfire that can quickly damage the catalytic converter and, in some cases, the engine itself. If the light is flashing, reduce your speed immediately and stop driving as soon as it’s safe.
Some cars have both yellow and red warning lights. If yours does, treat the colors as you would when approaching a stoplight.
Quick DIY checks you can do right away
Once you’re safely stopped, there are a few things worth doing:
Check the gas cap.
If you recently fueled up, make sure the cap is tightened until it clicks. A loose gas cap is one of the most common causes of a check engine light. After tightening it, the light may turn off once the system rechecks for leaks.
Open up your car’s app.
Many newer cars come with telematics you can easily access, either through a downloadable app or your vehicle’s infotainment screen.
Scan for codes if you have a reader.
If you have an older vehicle and own an OBD-II code reader or a Bluetooth adapter with a phone app like Torque or OBD Fusion, plug it into the diagnostic port (usually under the dash near the steering column). Codes like P0301 (misfire) or P0442 (EVAP leak) will give you a direction for next steps.
Here’s how to pull the codes:
Turn the ignition off and plug the scanner into the port.
Turn the ignition to “ON” (engine off) to power up the scanner
Select “Read Codes” or “Diagnostic” on the scanner (or app)
Once you see a code (or codes), consult your owner’s manual or a reputable database before deciding on repairs. Remember to clear the codes only after you’ve recorded them. Clearing them too early can erase helpful diagnostic information.
The common culprits and how to proceed
If you don’t have an app, code reader, or the mechanical knowledge and inclination to resolve the issue yourself, you’ll definitely want to take your vehicle to a trusted mechanic sooner rather than later. Their technicians will often start by looking for:
Failed oxygen sensors
Ignition problems (typically the spark plugs or coils)
Mass airflow sensor faults
EVAP system leaks
Catalytic converter problems
While some repairs may be costly, delaying them can be even more expensive. Even if your car seems to be running OK after displaying a check engine light, every additional mile you drive can add hundreds or thousands of dollars in damage.
Should you receive a repair estimate that seems cost-prohibitive, you might want to consider whether it makes more sense to replace rather than repair, especially if your vehicle is up there in mileage.
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