OBD2 Fault Code Library

Free lookup for thousands of OBD2 trouble codes: filter by family, read short meanings, and open deeper articles. Desktop ELM327 scanner with live data and AI guidance.

OBD2 symptoms

Look up diagnostic trouble codes by what the car is doing: misfire, overheating, rough idle, a check engine light, and other common symptoms.

• Engine misfire
• Engine overheating
• Rough idle
• Check engine light
• Poor fuel economy
• Hard starting
• Engine stalling
• Catalytic converter efficiency
• Oxygen sensor fault
• EVAP leak
• Thermostat not reaching temperature
• Lean air-fuel mixture
• Rich air-fuel mixture
• EGR flow fault
• Engine knock
• Charging system
• Throttle position
• Mass airflow sensor
• Turbo underboost
• Coolant temperature sensor
• Transmission fault

• P043D — Catalyst Temperature Sensor Circuit High (Bank 2 Sensor 2) (P043D): a powertrain (engine/transmission) fault affecting the catalytic converter efficiency monitoring. The car is usually drivable while you plan the repair. Most often caused by engine misfires damaging the catalyst, oil or coolant entering the exhaust, faulty downstream or upstream oxygen sensor.
• P043E — OBD2 code P043E flags a problem with the evaporative emission (EVAP) system (evaporative emission system leak detection reference orifice low flow). The car is usually drivable while you plan the repair. Common culprits: loose, damaged or wrong fuel cap, faulty purge valve (canister purge solenoid), small leak in the fuel tank or filler neck.
• P043F — P043F — Evaporative Emission System Leak Detection Reference Orifice High Flow. A fault in the evaporative emission (EVAP) system. The car is usually drivable while you plan the repair. Typical causes: cracked EVAP hoses or lines, faulty purge valve (canister purge solenoid), faulty vent valve or leak detection pump.
• P0440 — P0440 — Evaporative Emission Control System Malfunction. A fault in the evaporative emission (EVAP) system. The car is usually drivable while you plan the repair. Typical causes: cracked EVAP hoses or lines, faulty purge valve (canister purge solenoid), loose, damaged or wrong fuel cap.
• P0441 — P0441 — Evaporative Emission Control System Incorrect Purge Flow. A fault in the evaporative emission (EVAP) system. The car is usually drivable while you plan the repair. Typical causes: faulty purge valve (canister purge solenoid), saturated or damaged charcoal canister, loose, damaged or wrong fuel cap.
• P0442 — P0442 — Evaporative Emission Control System Leak Detected (small leak). A fault in the evaporative emission (EVAP) system. The car is usually drivable while you plan the repair. Typical causes: faulty vent valve or leak detection pump, faulty purge valve (canister purge solenoid), cracked EVAP hoses or lines.
• P0443 — P0443 — Evaporative Emission Control System Purge Control Valve Circuit. A fault in the evaporative emission (EVAP) system. The car is usually drivable while you plan the repair. Typical causes: faulty vent valve or leak detection pump, cracked EVAP hoses or lines, loose, damaged or wrong fuel cap.
• P0444 — P0444 — Evaporative Emission Control System Purge Control Valve Circuit Open. A fault in the evaporative emission (EVAP) system. The car is usually drivable while you plan the repair. Typical causes: cracked EVAP hoses or lines, faulty vent valve or leak detection pump, loose, damaged or wrong fuel cap.
• P0445 — P0445 — Evaporative Emission Control System Purge Control Valve Circuit Shorted. A fault in the evaporative emission (EVAP) system. The car is usually drivable while you plan the repair. Typical causes: faulty vent valve or leak detection pump, small leak in the fuel tank or filler neck, faulty purge valve (canister purge solenoid).
• P0446 — OBD2 code P0446 flags a problem with the evaporative emission (EVAP) system (evaporative emission control system vent control circuit malfunction). The car is usually drivable while you plan the repair. Common culprits: cracked EVAP hoses or lines, faulty purge valve (canister purge solenoid), loose, damaged or wrong fuel cap.
• P0447 — OBD2 code P0447 flags a problem with the evaporative emission (EVAP) system (evaporative emission control system vent control circuit open). The car is usually drivable while you plan the repair. Common culprits: saturated or damaged charcoal canister, cracked EVAP hoses or lines, small leak in the fuel tank or filler neck.
• P0448 — Evaporative Emission Control System Vent Control Circuit Shorted (P0448): a powertrain (engine/transmission) fault affecting the evaporative emission (EVAP) system. The car is usually drivable while you plan the repair. Most often caused by saturated or damaged charcoal canister, faulty vent valve or leak detection pump, faulty purge valve (canister purge solenoid).
• P0449 — P0449 — Evaporative Emission Control System Vent Valve/Solenoid Circuit Malfunction. A fault in the evaporative emission (EVAP) system. The car is usually drivable while you plan the repair. Typical causes: faulty vent valve or leak detection pump, faulty purge valve (canister purge solenoid), saturated or damaged charcoal canister.
• P044A — OBD2 code P044A flags a problem with the exhaust gas recirculation (EGR) system (exhaust gas recirculation sensor "C" circuit). The car is usually drivable while you plan the repair. Common culprits: failed EGR valve or position sensor, vacuum leaks in EGR control lines, faulty EGR solenoid or wiring.
• P044B — OBD2 code P044B flags a problem with the exhaust gas recirculation (EGR) system (exhaust gas recirculation sensor "C" circuit range/performance). The car is usually drivable while you plan the repair. Common culprits: vacuum leaks in EGR control lines, failed EGR valve or position sensor, ECM control circuit fault.
• P044C — P044C — Exhaust Gas Recirculation Sensor "C" Circuit Low. A fault in the exhaust gas recirculation (EGR) system. The car is usually drivable while you plan the repair. Typical causes: failed EGR valve or position sensor, carbon buildup blocking the EGR valve or passages, faulty EGR solenoid or wiring.
• P044D — OBD2 code P044D flags a problem with the exhaust gas recirculation (EGR) system (exhaust gas recirculation sensor "C" circuit high). The car is usually drivable while you plan the repair. Common culprits: vacuum leaks in EGR control lines, carbon buildup blocking the EGR valve or passages, failed EGR valve or position sensor.
• P044E — P044E — Exhaust Gas Recirculation Sensor "C" Circuit Intermittent/Erratic. A fault in the exhaust gas recirculation (EGR) system. The car is usually drivable while you plan the repair. Typical causes: carbon buildup blocking the EGR valve or passages, faulty EGR solenoid or wiring, failed EGR valve or position sensor.
• P044F — OBD2 code P044F flags a problem with the sensor and actuator circuits (secondary air injection system switching valve "A" circuit high). The car is usually drivable while you plan the repair. Common culprits: blown fuse feeding the circuit, corroded, loose or damaged connector, open or shorted wiring in the circuit.
• P0450 — OBD2 code P0450 flags a problem with the evaporative emission (EVAP) system (evaporative emission control system pressure sensor malfunction). The car is usually drivable while you plan the repair. Common culprits: loose, damaged or wrong fuel cap, saturated or damaged charcoal canister, small leak in the fuel tank or filler neck.
• P0451 — P0451 — Evaporative Emission Control System Pressure Sensor Range/Performance. A fault in the evaporative emission (EVAP) system. The car is usually drivable while you plan the repair. Typical causes: saturated or damaged charcoal canister, loose, damaged or wrong fuel cap, small leak in the fuel tank or filler neck.
• P0452 — OBD2 code P0452 flags a problem with the evaporative emission (EVAP) system (evaporative emission control system pressure sensor low input). The car is usually drivable while you plan the repair. Common culprits: faulty vent valve or leak detection pump, faulty purge valve (canister purge solenoid), small leak in the fuel tank or filler neck.
• P0453 — Evaporative Emission Control System Pressure Sensor High Input (P0453): a powertrain (engine/transmission) fault affecting the evaporative emission (EVAP) system. The car is usually drivable while you plan the repair. Most often caused by saturated or damaged charcoal canister, faulty vent valve or leak detection pump, small leak in the fuel tank or filler neck.
• P0454 — P0454 — Evaporative Emission Control System Pressure Sensor Intermittent. A fault in the evaporative emission (EVAP) system. The car is usually drivable while you plan the repair. Typical causes: faulty vent valve or leak detection pump, small leak in the fuel tank or filler neck, saturated or damaged charcoal canister.