Trouble codes › By vehicle › Hyundai Elantra
Common check-engine codes on the Hyundai Elantra
2007-2023
Elantras are common commuter cars; codes are mostly catalytic converters, oxygen sensors, EVAP and misfires. Hyundai has run engine recalls and extended warranties on several of its models and years, so check your VIN for open campaigns.
Most common: P0420, P0300, P0171, P0441, P0456, P0128.
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 Hyundai Elantra: Catalyst efficiency at higher mileage; fix misfires and check oil consumption 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 Hyundai Elantra: Misfires: plugs and coils first. A misfire that comes with knocking or a new engine noise needs checking right away; ask a Hyundai dealer whether any engine campaign covers your VIN.
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 Hyundai Elantra: Lean: vacuum leaks or a dirty sensor.
P0171: causes, can I keep driving, and what to check first →
P0441 Evaporative Emission System Incorrect Purge Flow
P0441 means the EVAP purge system isn't flowing fuel vapor to the engine as expected, often a stuck purge valve.
On the Hyundai Elantra: EVAP purge flow: the purge valve is a common fix.
P0441: 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 Hyundai Elantra: Very small EVAP leaks: start with the gas cap.
P0456: causes, can I keep driving, and what to check first →
P0128 Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)
P0128 means the engine isn't reaching normal operating temperature, almost always a thermostat stuck open.
On the Hyundai Elantra: Thermostat stuck open.
P0128: 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.