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

• P02B4 — OBD2 code P02B4 flags a problem with the fuel delivery and mixture control (cylinder 7 - injector restricted). Short, gentle driving to a shop is usually possible. Common culprits: faulty fuel pressure regulator, vacuum or intake leaks skewing the mixture, clogged or leaking fuel injectors.
• P02B5 — OBD2 code P02B5 flags a problem with the fuel delivery and mixture control (cylinder 7 - injector leaking). Short, gentle driving to a shop is usually possible. Common culprits: faulty fuel pressure regulator, weak fuel pump or clogged fuel filter, clogged or leaking fuel injectors.
• P02B6 — OBD2 code P02B6 flags a problem with the fuel delivery and mixture control (cylinder 8 - fuel trim at max limit). Short, gentle driving to a shop is usually possible. Common culprits: vacuum or intake leaks skewing the mixture, contaminated or incorrect fuel, clogged or leaking fuel injectors.
• P02B7 — OBD2 code P02B7 flags a problem with the fuel delivery and mixture control (cylinder 8 - fuel trim at min limit). Short, gentle driving to a shop is usually possible. Common culprits: faulty fuel pressure regulator, faulty fuel rail pressure sensor or wiring, vacuum or intake leaks skewing the mixture.
• P02B8 — OBD2 code P02B8 flags a problem with the fuel delivery and mixture control (cylinder 8 - injector restricted). Short, gentle driving to a shop is usually possible. Common culprits: faulty fuel pressure regulator, vacuum or intake leaks skewing the mixture, contaminated or incorrect fuel.
• P02B9 — Cylinder 8 - Injector Leaking (P02B9): a powertrain (engine/transmission) fault affecting the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Most often caused by contaminated or incorrect fuel, faulty fuel pressure regulator, weak fuel pump or clogged fuel filter.
• P02BA — OBD2 code P02BA flags a problem with the fuel delivery and mixture control (cylinder 9 - fuel trim at max limit). Short, gentle driving to a shop is usually possible. Common culprits: faulty fuel pressure regulator, clogged or leaking fuel injectors, faulty fuel rail pressure sensor or wiring.
• P02BB — Cylinder 9 - Fuel Trim at Min Limit (P02BB): a powertrain (engine/transmission) fault affecting the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Most often caused by faulty fuel pressure regulator, weak fuel pump or clogged fuel filter, faulty fuel rail pressure sensor or wiring.
• P02BC — Cylinder 9 - Injector Restricted (P02BC): a powertrain (engine/transmission) fault affecting the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Most often caused by clogged or leaking fuel injectors, weak fuel pump or clogged fuel filter, vacuum or intake leaks skewing the mixture.
• P02BD — P02BD — Cylinder 9 - Injector Leaking. A fault in the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Typical causes: vacuum or intake leaks skewing the mixture, contaminated or incorrect fuel, faulty fuel rail pressure sensor or wiring.
• P02BE — OBD2 code P02BE flags a problem with the fuel delivery and mixture control (cylinder 10 - fuel trim at max limit). Short, gentle driving to a shop is usually possible. Common culprits: clogged or leaking fuel injectors, weak fuel pump or clogged fuel filter, vacuum or intake leaks skewing the mixture.
• P02BF — OBD2 code P02BF flags a problem with the fuel delivery and mixture control (cylinder 10 - fuel trim at min limit). Short, gentle driving to a shop is usually possible. Common culprits: contaminated or incorrect fuel, faulty fuel pressure regulator, weak fuel pump or clogged fuel filter.
• P02C0 — Cylinder 10 - Injector Restricted (P02C0): a powertrain (engine/transmission) fault affecting the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Most often caused by faulty fuel pressure regulator, weak fuel pump or clogged fuel filter, faulty fuel rail pressure sensor or wiring.
• P02C1 — P02C1 — Cylinder 10 - Injector Leaking. A fault in the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Typical causes: faulty fuel pressure regulator, vacuum or intake leaks skewing the mixture, faulty fuel rail pressure sensor or wiring.
• P02C2 — P02C2 — Cylinder 11 - Fuel Trim at Max Limit. A fault in the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Typical causes: faulty fuel pressure regulator, clogged or leaking fuel injectors, contaminated or incorrect fuel.
• P02C3 — Cylinder 11 - Fuel Trim at Min Limit (P02C3): a powertrain (engine/transmission) fault affecting the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Most often caused by faulty fuel rail pressure sensor or wiring, faulty fuel pressure regulator, contaminated or incorrect fuel.
• P02C4 — OBD2 code P02C4 flags a problem with the fuel delivery and mixture control (cylinder 11 - injector restricted). Short, gentle driving to a shop is usually possible. Common culprits: contaminated or incorrect fuel, clogged or leaking fuel injectors, vacuum or intake leaks skewing the mixture.
• P02C5 — Cylinder 11 - Injector Leaking (P02C5): a powertrain (engine/transmission) fault affecting the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Most often caused by contaminated or incorrect fuel, faulty fuel pressure regulator, faulty fuel rail pressure sensor or wiring.
• P02C6 — Cylinder 12 - Fuel Trim at Max Limit (P02C6): a powertrain (engine/transmission) fault affecting the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Most often caused by weak fuel pump or clogged fuel filter, clogged or leaking fuel injectors, vacuum or intake leaks skewing the mixture.
• P02C7 — OBD2 code P02C7 flags a problem with the fuel delivery and mixture control (cylinder 12 - fuel trim at min limit). Short, gentle driving to a shop is usually possible. Common culprits: vacuum or intake leaks skewing the mixture, faulty fuel pressure regulator, contaminated or incorrect fuel.
• P02C8 — P02C8 — Cylinder 12 - Injector Restricted. A fault in the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Typical causes: clogged or leaking fuel injectors, vacuum or intake leaks skewing the mixture, weak fuel pump or clogged fuel filter.
• P02C9 — OBD2 code P02C9 flags a problem with the fuel delivery and mixture control (cylinder 12 - injector leaking). Short, gentle driving to a shop is usually possible. Common culprits: contaminated or incorrect fuel, faulty fuel pressure regulator, weak fuel pump or clogged fuel filter.
• P02CA — OBD2 code P02CA flags a problem with the turbocharger / supercharger boost control (turbocharger/supercharger "B" overboost condition). Short, gentle driving to a shop is usually possible. Common culprits: worn turbocharger, boost leak in intercooler piping or hoses, vacuum or actuator line damage.
• P02CB — Turbocharger/Supercharger "B" Underboost Condition (P02CB): a powertrain (engine/transmission) fault affecting the turbocharger / supercharger boost control. Short, gentle driving to a shop is usually possible. Most often caused by boost leak in intercooler piping or hoses, vacuum or actuator line damage, clogged intake or exhaust (DPF/cat).