Advice September 28, 2026, 4 minute read
Check engine light on? Here's what to do in the next 24 hours
Steady versus flashing, the five most common codes we see in metro Detroit, and why the scan is free at all 8 Redford Auto shops.
The check engine light is the most ignored light on the dash. Most of the time it's something small. Occasionally it's the difference between a $90 sensor and a $1,500 catalytic converter.
Steady light: schedule it this week
A steady light means the computer saw a fault and stored a code. The car is driveable. Swing by any shop and we'll read the code for free while you wait.
Flashing light: pull over
A flashing light means an active misfire. Unburned fuel is going into the exhaust, where it overheats the catalytic converter. Fifteen minutes of driving can turn a spark plug problem into a converter replacement.
The codes we see most
- P0420: catalytic converter efficiency. Often an oxygen sensor, sometimes the converter.
- P0300 to P0308: misfire. Plugs, coils or a vacuum leak.
- P0171 / P0174: running lean. Usually a vacuum leak or a dirty mass airflow sensor.
- P0455 / P0456: EVAP leak. Start with the gas cap.
- P0128: coolant temperature. Usually a thermostat.
Why the scan is free
Reading the code takes two minutes and tells us where to look. It does not tell us what to replace. If the fix needs real diagnosis, you'll get a quote for that first.