Spark plugs, ignition coils and check engine lights

Signs something's wrong

• A check engine light, on or flashing
• Rough idle or shaking
• Hesitation when you accelerate
• Worse gas mileage than usual
• The car drops into limp mode

What we do

• Spark plugs and ignition coils
• Check engine light diagnosis with a dealer-level scan tool
• Oxygen (O2) sensors and other engine sensors
• Codes cleared and rechecked after the repair

Worth knowing

A flashing check engine light means an active misfire. Take it easy and get it looked at soon, because driving on a misfire can damage the catalytic converter.

Start with the basics. We once looked at an SUV that had been quoted for a whole new engine. The real problem was fouled spark plugs and worn-out coils. We replaced them in the driveway and it ran smooth the same day. Sometimes an engine really is done, but when the simple stuff hasn't been checked, it's worth checking first.

A code is a starting point. Parts stores will read one for free, and that's a good first step. The code tells you where to look, not always which part to buy.