What happens when I ignore the CHECK ENGINE LIGHT?
There are two kinds of CHECK ENGINE LIGHT alerts. A non-flashing but lit CHECK ENGINE LIGHT, is usually a less severe problem that shouldn’t cause immediate problems but needs to be checked as soon as possible. Also, a flashing and illuminated CHECK ENGINE LIGHT means your vehicle senses a critical system error (such as a major cylinder misfire ) and you need immediate attention before potentially breaking down and possibly damaging other critical and expensive parts. In this case, continuing to drive can lead to further damage rather quickly or can leave you stranded.
Driving the vehicle with a non-flashing generic code will almost certainly cause an increase in emissions and a decrease in fuel economy-which can be robbing you of up to 20% fuel efficiency at each fill-up. Looking at it a different way, based on $3 per gallon, typically you could be wasting $7.50 per fill-up or upwards of $300 per year.
As quite a few of the systems work interdependent of one another, an error in one system can affect the operation in another. EVAP codes (vacuum related), EGR, temperature, speed sensors, etc. can all have an effect on how the transmission acts and shifts or how the engine performs or the cooling fans turn on, etc. Ignoring these important warnings may create other critical issues.
Finally, if you live in one of the areas that require it, you certainly cannot pass state mandated Emission/Smog inspection with your CHECK ENGINE LIGHT