Check Engine Light Code Lookup
Got a code from AutoZone? Find out what it means and what to do next
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Catalyst System Efficiency Below Threshold (Bank 1)
Your catalytic converter isn't cleaning exhaust gases properly. This is like your car's air filter being clogged - it still runs but isn't doing its job well.
System Too Lean (Bank 1)
Your engine is getting too much air or not enough fuel - like trying to start a fire with wet wood. It'll run rough and use more gas.
Random/Multiple Cylinder Misfire Detected
Your engine is stuttering like a scratched CD - multiple cylinders aren't firing properly, making it run rough.
Coolant Thermostat Temperature Below Regulating Temperature
Your engine isn't warming up properly - like leaving your house door open in winter. Uses more gas and wears engine faster.
EVAP Emission Control System Small Leak Detected
Your gas tank vapor system has a tiny leak - like a pinhole in a balloon. Won't affect driving but fails emissions tests.
EVAP Emission Control System Large Leak Detected
Your gas tank vapor system has a big leak - like leaving your gas cap off. You might smell gas and fail emissions.
Cylinder 1 Misfire Detected
Cylinder #1 isn't firing right - like running on 3 cylinders instead of 4. You'll feel shaking and lose power.
Cylinder 2 Misfire Detected
Cylinder #2 isn't working right - your engine is limping along with reduced power and shaking.
Cylinder 3 Misfire Detected
Cylinder #3 is misfiring - like having a runner with a injured leg, the engine struggles and shakes.
Cylinder 4 Misfire Detected
Cylinder #4 isn't firing - your engine is running unbalanced, causing shaking and power loss.
EGR Flow Insufficient Detected
Your emissions control system is clogged - like a blocked drain. Engine runs hotter and produces more pollution.
EVAP Emission Control System Very Small Leak Detected
Tiny vapor leak in your fuel system - like a microscopic hole. Won't affect driving but needs fixing for emissions.
System Too Rich (Bank 1)
Your engine is getting too much gas - like flooding a campfire with lighter fluid. Wastes fuel and can damage parts.
Camshaft Position Timing Over-Advanced (Bank 1)
Your engine's valve timing is off - like a drummer playing too fast. Causes rough running and poor performance.
Catalyst System Efficiency Below Threshold (Bank 2)
Your second catalytic converter (V6/V8 engines) isn't cleaning exhaust properly. Like having one lung not working well.
Vehicle Speed Sensor Malfunction
Your car's speedometer sensor isn't working - the computer doesn't know how fast you're going. May affect shifting.
Idle Air Control System RPM Higher Than Expected
Your engine is idling too fast - like having your foot slightly on the gas pedal all the time. Wastes fuel.
Transmission Control System Malfunction
Your transmission computer detected a problem - like a warning that something in the transmission needs attention.
Intake Air Temperature Sensor High Input
The sensor that measures incoming air temperature is broken - computer can't adjust fuel mixture properly.
Crankshaft Position Sensor Circuit Malfunction
The sensor that tells the computer when to fire spark plugs isn't working - engine may not start or dies randomly.
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Understanding Check Engine Light Codes
What are OBD2 Codes?
OBD2 (On-Board Diagnostics II) codes are standardized diagnostic trouble codes that your vehicle's computer generates when it detects a problem. These codes help mechanics quickly identify issues with your engine, transmission, emissions system, and more.
While code readers at auto parts stores can tell you the code, they don't provide the full diagnostic picture. Professional diagnosis considers multiple factors including vehicle history, related codes, and physical inspection.
Code Format Explained
Important Safety Note
A flashing check engine light indicates a severe misfire that can damage your catalytic converter within minutes. If your light is flashing, reduce speed, avoid heavy acceleration, and get to a repair shop immediately. Continuing to drive can result in thousands of dollars in additional damage.
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