Trouble codes › By vehicle › Honda Civic
Common check-engine codes on the Honda Civic
2006-2023
Civics are reliable, so most codes are wear items at higher mileage: catalytic converters, oxygen sensors, EVAP and misfires. Honda also uses some of its own codes (P1xxx and P26xx VTEC codes) that need Honda service information.
Most common: P0420, P0300, P0171, P0141, P0456, P0457.
P0420 Catalyst System Efficiency Below Threshold (Bank 1)
P0420 means the catalytic converter on bank 1 isn't cleaning the exhaust well enough, usually a worn converter, an exhaust leak or a lazy oxygen sensor.
On the Honda Civic: Catalyst efficiency at higher mileage; check for exhaust leaks and any misfire first.
P0420: causes, can I keep driving, and what to check first →
P0300 Random/Multiple Cylinder Misfire Detected
P0300 means the engine is misfiring in more than one cylinder, often from worn plugs or coils, a vacuum leak or low fuel pressure.
On the Honda Civic: Misfires, often on one cylinder (P0301-P0304): spark plugs at their interval, then coils. Valve clearance that's out of adjustment can also cause misfires on Hondas; it's part of Honda's maintenance schedule.
P0300: causes, can I keep driving, and what to check first →
P0171 System Too Lean (Bank 1)
P0171 means bank 1 is running lean (too much air or too little fuel), most often from a vacuum leak or a dirty MAF sensor.
On the Honda Civic: Lean: vacuum leaks, a dirty MAF sensor (on engines that have one) or a failing air-fuel sensor.
P0171: causes, can I keep driving, and what to check first →
P0141 O2 Sensor Heater Circuit (Bank 1 Sensor 2)
P0141 means the heater in bank 1's rear oxygen sensor isn't working, usually burned out or missing power.
On the Honda Civic: Rear oxygen sensor heater: a common Honda code at higher mileage, usually the sensor itself.
P0141: causes, can I keep driving, and what to check first →
P0456 Evaporative Emission System Leak Detected (Very Small Leak)
P0456 means the EVAP system has a very small leak, often a gas cap that isn't sealing perfectly.
On the Honda Civic: Very small EVAP leaks: the gas cap is the most common fix, then the EVAP canister or purge valve.
P0456: causes, can I keep driving, and what to check first →
P0457 Evaporative Emission System Leak Detected (Fuel Cap Loose/Off)
P0457 means the gas cap is loose, off or not sealing.
On the Honda Civic: Honda shows a fuel cap message and P0457 when the cap wasn't tightened after refueling.
P0457: causes, can I keep driving, and what to check first →
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Common codes and known problems as widely reported for these model years; your vehicle may differ. Check nhtsa.gov/recalls and ask a dealer about service bulletins for your VIN, and confirm in your service information.