Trouble codes › By vehicle › Toyota Corolla
Common check-engine codes on the Toyota Corolla
2003-2023
Corollas are among the most reliable cars on the road, so codes tend to be high-mileage wear: catalytic converters, oxygen sensors and EVAP. Some 2009-2011 1.8L engines can burn oil.
Most common: P0420, P0171, P0136, P2195, P0441, P0300.
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 Toyota Corolla: One of the most common Corolla codes past about 150,000 miles. Check oil consumption and for exhaust leaks before replacing the converter.
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 Toyota Corolla: Lean: a dirty MAF sensor or a vacuum leak.
P0171: causes, can I keep driving, and what to check first →
P0136 O2 Sensor Circuit (Bank 1 Sensor 2)
P0136 means the engine computer isn't getting a sensible signal from bank 1's rear oxygen sensor (after the catalytic converter).
On the Toyota Corolla: Rear oxygen sensor circuit faults are common at higher mileage.
P0136: causes, can I keep driving, and what to check first →
P2195 O2 Sensor Signal Biased/Stuck Lean (Bank 1 Sensor 1)
P2195 means bank 1's front oxygen sensor reads lean when it shouldn't, from a leak, a dirty MAF or an aging sensor.
On the Toyota Corolla: Front air-fuel sensor reading lean: an aging sensor or an exhaust leak.
P2195: 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 Toyota Corolla: EVAP purge flow: the purge valve or canister.
P0441: 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 Toyota Corolla: Misfires: plugs and coils; on oil-burning engines, fouled plugs.
P0300: 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.