The check engine light, also called the malfunction indicator lamp, comes on when your engine control module sees a problem that could affect emissions or engine performance. It is connected to the on-board diagnostics system (OBD-II) that has been required on cars sold in the US since 1996.
Some causes are minor, like a loose gas cap. Others, like a misfire, can damage your catalytic converter if ignored. In California the light also matters at smog time, because a vehicle with the check engine light on will not pass a smog inspection.
What a check engine light can mean
- A loose or damaged gas cap causing an evaporative emissions leak
- An engine misfire from worn spark plugs, ignition coils or injectors
- A failing oxygen sensor or mass airflow sensor
- A catalytic converter that is no longer working efficiently
- Vacuum leaks, EGR problems or thermostat faults
Steady versus flashing
A steady light means a fault has been stored. The car is usually safe to drive to the shop, but you should have it checked soon, because small problems often become expensive ones. A flashing light usually indicates a severe misfire that can overheat the catalytic converter. Reduce speed, avoid hard acceleration and call us.
We read the code, review the freeze-frame data showing the conditions when it set, and test the circuit or component involved. After the repair we clear the code and confirm the readiness monitors are running, so you know the fix held.
Driving in Concord and Contra Costa County
Because California smog inspections require the light to be off and the monitors to be ready, we often see drivers from around Contra Costa County shortly before their DMV renewal. Fixing the light early gives the monitors time to reset before your smog test.
Questions about check engine light
Will a check engine light clear itself?
Sometimes, if the fault was temporary, such as a loose gas cap that has been tightened. If the underlying problem is still there, the light will come back.
Can I pass smog with the check engine light on?
No. In California a vehicle with the malfunction indicator lamp illuminated fails the smog inspection.
Is it expensive to diagnose?
We explain the diagnostic charge up front and give you an estimate for the repair before any work begins.
Published by Anywhere Automotive, Concord, CA. Diagnosis and pricing are confirmed after inspection.