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

• P2445 — OBD2 code P2445 flags a problem with the sensor and actuator circuits (secondary air injection system pump stuck off bank 1). The car is usually drivable while you plan the repair. Common culprits: poor ground connection, control module driver fault, blown fuse feeding the circuit.
• P2446 — P2446 — Secondary Air Injection System Pump Stuck On Bank 2. A fault in the sensor and actuator circuits. The car is usually drivable while you plan the repair. Typical causes: blown fuse feeding the circuit, corroded, loose or damaged connector, control module driver fault.
• P2447 — OBD2 code P2447 flags a problem with the sensor and actuator circuits (secondary air injection system pump stuck off bank 2). The car is usually drivable while you plan the repair. Common culprits: poor ground connection, control module driver fault, blown fuse feeding the circuit.
• P2448 — Secondary Air Injection System High Air Flow Bank 1 (P2448): a powertrain (engine/transmission) fault affecting the sensor and actuator circuits. The car is usually drivable while you plan the repair. Most often caused by blown fuse feeding the circuit, corroded, loose or damaged connector, faulty sensor or actuator of the affected circuit.
• P2449 — Secondary Air Injection System High Air Flow Bank 2 (P2449): a powertrain (engine/transmission) fault affecting the sensor and actuator circuits. The car is usually drivable while you plan the repair. Most often caused by blown fuse feeding the circuit, control module driver fault, faulty sensor or actuator of the affected circuit.
• P244A — OBD2 code P244A flags a problem with the diesel particulate filter (DPF) (diesel particulate filter differential pressure too low bank 1). Short, gentle driving to a shop is usually possible. Common culprits: failed regeneration due to sensor or wiring faults, excessive ash loading (end of DPF life), faulty differential pressure or exhaust temperature sensor.
• P244B — OBD2 code P244B flags a problem with the diesel particulate filter (DPF) (diesel particulate filter differential pressure too high bank 1). Short, gentle driving to a shop is usually possible. Common culprits: failed regeneration due to sensor or wiring faults, engine faults producing excess soot (EGR, injectors), faulty differential pressure or exhaust temperature sensor.
• P244C — P244C — Exhaust Temperature Too Low For Particulate Filter Regeneration Bank 1. A fault in the diesel particulate filter (DPF). Short, gentle driving to a shop is usually possible. Typical causes: engine faults producing excess soot (EGR, injectors), soot-overloaded DPF from short-trip driving, failed regeneration due to sensor or wiring faults.
• P244D — P244D — Exhaust Temperature Too High For Particulate Filter Regeneration Bank 1. A fault in the diesel particulate filter (DPF). Short, gentle driving to a shop is usually possible. Typical causes: engine faults producing excess soot (EGR, injectors), failed regeneration due to sensor or wiring faults, excessive ash loading (end of DPF life).
• P244E — Exhaust Temperature Too Low For Particulate Filter Regeneration Bank 2 (P244E): a powertrain (engine/transmission) fault affecting the diesel particulate filter (DPF). Short, gentle driving to a shop is usually possible. Most often caused by faulty differential pressure or exhaust temperature sensor, failed regeneration due to sensor or wiring faults, engine faults producing excess soot (EGR, injectors).
• P244F — OBD2 code P244F flags a problem with the diesel particulate filter (DPF) (exhaust temperature too high for particulate filter regeneration bank 2). Short, gentle driving to a shop is usually possible. Common culprits: excessive ash loading (end of DPF life), faulty differential pressure or exhaust temperature sensor, soot-overloaded DPF from short-trip driving.
• P2450 — Evaporative Emission System Switching Valve Performance/Stuck Open (P2450): 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 faulty purge valve (canister purge solenoid), loose, damaged or wrong fuel cap, faulty vent valve or leak detection pump.
• P2451 — Evaporative Emission System Switching Valve Stuck Closed (P2451): 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 cracked EVAP hoses or lines, saturated or damaged charcoal canister, faulty vent valve or leak detection pump.
• P2454 — OBD2 code P2454 flags a problem with the diesel particulate filter (DPF) (diesel particulate filter pressure sensor "A" circuit low). Short, gentle driving to a shop is usually possible. Common culprits: faulty differential pressure or exhaust temperature sensor, failed regeneration due to sensor or wiring faults, soot-overloaded DPF from short-trip driving.
• P2455 — OBD2 code P2455 flags a problem with the diesel particulate filter (DPF) (diesel particulate filter pressure sensor "A" circuit high). Short, gentle driving to a shop is usually possible. Common culprits: excessive ash loading (end of DPF life), failed regeneration due to sensor or wiring faults, faulty differential pressure or exhaust temperature sensor.
• P2456 — P2456 — Diesel Particulate Filter Pressure Sensor "A" Circuit Intermittent/Erratic. A fault in the diesel particulate filter (DPF). Short, gentle driving to a shop is usually possible. Typical causes: faulty differential pressure or exhaust temperature sensor, failed regeneration due to sensor or wiring faults, soot-overloaded DPF from short-trip driving.
• P2457 — Exhaust Gas Recirculation Cooling System Performance (P2457): a powertrain (engine/transmission) fault affecting the exhaust gas recirculation (EGR) system. The car is usually drivable while you plan the repair. Most often caused by faulty EGR solenoid or wiring, ECM control circuit fault, carbon buildup blocking the EGR valve or passages.
• P2458 — OBD2 code P2458 flags a problem with the diesel particulate filter (DPF) (diesel particulate filter regeneration duration). Short, gentle driving to a shop is usually possible. Common culprits: faulty differential pressure or exhaust temperature sensor, failed regeneration due to sensor or wiring faults, engine faults producing excess soot (EGR, injectors).
• P245A — P245A — Exhaust Gas Recirculation Cooler Bypass Control Circuit/Open. A fault in the exhaust gas recirculation (EGR) system. The car is usually drivable while you plan the repair. Typical causes: ECM control circuit fault, carbon buildup blocking the EGR valve or passages, vacuum leaks in EGR control lines.
• P245B — Exhaust Gas Recirculation Cooler Bypass Control Circuit Range/Performance (P245B): a powertrain (engine/transmission) fault affecting the exhaust gas recirculation (EGR) system. The car is usually drivable while you plan the repair. Most often caused by faulty EGR solenoid or wiring, vacuum leaks in EGR control lines, failed EGR valve or position sensor.
• P245C — P245C — Exhaust Gas Recirculation Cooler Bypass Control Circuit Low. A fault in the exhaust gas recirculation (EGR) system. The car is usually drivable while you plan the repair. Typical causes: vacuum leaks in EGR control lines, failed EGR valve or position sensor, faulty EGR solenoid or wiring.
• P245D — OBD2 code P245D flags a problem with the exhaust gas recirculation (EGR) system (exhaust gas recirculation cooler bypass control circuit high). The car is usually drivable while you plan the repair. Common culprits: failed EGR valve or position sensor, ECM control circuit fault, carbon buildup blocking the EGR valve or passages.
• P245E — OBD2 code P245E flags a problem with the diesel particulate filter (DPF) (diesel particulate filter pressure sensor "B" circuit). Short, gentle driving to a shop is usually possible. Common culprits: failed regeneration due to sensor or wiring faults, engine faults producing excess soot (EGR, injectors), faulty differential pressure or exhaust temperature sensor.
• P2460 — OBD2 code P2460 flags a problem with the diesel particulate filter (DPF) (diesel particulate filter pressure sensor "B" circuit low). Short, gentle driving to a shop is usually possible. Common culprits: faulty differential pressure or exhaust temperature sensor, failed regeneration due to sensor or wiring faults, soot-overloaded DPF from short-trip driving.