Trouble codes › By vehicle › Honda Accord
Common check-engine codes on the Honda Accord
2003-2022
The Accord's common codes are mostly wear items, plus one well-known V6 issue: Variable Cylinder Management (VCM) on the 3.5L V6 (2008-2017), which turns off cylinders to save fuel and is linked to misfires and fouled plugs.
Most common: P0300, P0420, P0171, P0456, P0141, P0135.
Known problems on the Honda Accord
- Honda 3.5L V6 VCM misfires and fouled spark plugs (P0300, P0301, P0302, P0303)
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 Accord: On V6 Accords with VCM, misfires on cylinders that VCM shuts off (often the rear bank) are well known, linked to oil fouling the plugs and piston rings. Honda issued bulletins and software updates, and there was a class-action settlement for some years; check with a Honda dealer using your VIN.
P0300: causes, can I keep driving, and what to check first →
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 Accord: Catalyst efficiency at higher mileage; fix any misfire first.
P0420: 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 Accord: Lean: vacuum leaks, a dirty MAF sensor or an aging air-fuel sensor.
P0171: 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 Accord: Very small EVAP leaks: the gas cap first, then the canister and its valves.
P0456: 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 Accord: Rear oxygen sensor heater failures are common at higher mileage.
P0141: causes, can I keep driving, and what to check first →
P0135 O2 Sensor Heater Circuit (Bank 1, Sensor 1)
P0135 means the heater in bank 1's front oxygen sensor isn't working, usually burned out or missing power.
On the Honda Accord: Front oxygen or air-fuel sensor heater: usually the sensor.
P0135: 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.