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

• P029C — P029C — Cylinder 1 - Injector Restricted. A fault in the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Typical causes: contaminated or incorrect fuel, clogged or leaking fuel injectors, weak fuel pump or clogged fuel filter.
• P029D — Cylinder 1 - Injector Leaking (P029D): 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, faulty fuel rail pressure sensor or wiring, weak fuel pump or clogged fuel filter.
• P029E — OBD2 code P029E flags a problem with the fuel delivery and mixture control (cylinder 2 - fuel trim at max limit). Short, gentle driving to a shop is usually possible. Common culprits: weak fuel pump or clogged fuel filter, clogged or leaking fuel injectors, faulty fuel pressure regulator.
• P029F — Cylinder 2 - Fuel Trim at Min Limit (P029F): 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, contaminated or incorrect fuel, faulty fuel rail pressure sensor or wiring.
• P02A0 — P02A0 — Cylinder 2 - Injector Restricted. A fault in the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Typical causes: faulty fuel pressure regulator, faulty fuel rail pressure sensor or wiring, contaminated or incorrect fuel.
• P02A1 — Cylinder 2 - Injector Leaking (P02A1): 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, vacuum or intake leaks skewing the mixture, clogged or leaking fuel injectors.
• P02A2 — P02A2 — Cylinder 3 - 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 rail pressure sensor or wiring, contaminated or incorrect fuel, clogged or leaking fuel injectors.
• P02A3 — P02A3 — Cylinder 3 - Fuel Trim at Min Limit. A fault in the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Typical causes: faulty fuel rail pressure sensor or wiring, clogged or leaking fuel injectors, weak fuel pump or clogged fuel filter.
• P02A4 — Cylinder 3 - Injector Restricted (P02A4): 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 vacuum or intake leaks skewing the mixture, contaminated or incorrect fuel, weak fuel pump or clogged fuel filter.
• P02A5 — OBD2 code P02A5 flags a problem with the fuel delivery and mixture control (cylinder 3 - injector leaking). Short, gentle driving to a shop is usually possible. Common culprits: clogged or leaking fuel injectors, faulty fuel pressure regulator, faulty fuel rail pressure sensor or wiring.
• P02A6 — OBD2 code P02A6 flags a problem with the fuel delivery and mixture control (cylinder 4 - fuel trim at max limit). Short, gentle driving to a shop is usually possible. Common culprits: faulty fuel pressure regulator, weak fuel pump or clogged fuel filter, contaminated or incorrect fuel.
• P02A7 — Cylinder 4 - Fuel Trim at Min Limit (P02A7): 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 vacuum or intake leaks skewing the mixture, faulty fuel rail pressure sensor or wiring, faulty fuel pressure regulator.
• P02A8 — P02A8 — Cylinder 4 - Injector Restricted. A fault in the fuel delivery and mixture control. Short, gentle driving to a shop is usually possible. Typical causes: faulty fuel rail pressure sensor or wiring, weak fuel pump or clogged fuel filter, faulty fuel pressure regulator.
• P02A9 — Cylinder 4 - Injector Leaking (P02A9): 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, faulty fuel rail pressure sensor or wiring, clogged or leaking fuel injectors.
• P02AA — Cylinder 5 - Fuel Trim at Max Limit (P02AA): 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 vacuum or intake leaks skewing the mixture, faulty fuel pressure regulator, clogged or leaking fuel injectors.
• P02AB — OBD2 code P02AB flags a problem with the fuel delivery and mixture control (cylinder 5 - fuel trim at min limit). Short, gentle driving to a shop is usually possible. Common culprits: faulty fuel pressure regulator, clogged or leaking fuel injectors, vacuum or intake leaks skewing the mixture.
• P02AC — P02AC — Cylinder 5 - Injector Restricted. 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.
• P02AD — P02AD — Cylinder 5 - 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, contaminated or incorrect fuel, vacuum or intake leaks skewing the mixture.
• P02AE — OBD2 code P02AE flags a problem with the fuel delivery and mixture control (cylinder 6 - fuel trim at max limit). Short, gentle driving to a shop is usually possible. Common culprits: weak fuel pump or clogged fuel filter, clogged or leaking fuel injectors, vacuum or intake leaks skewing the mixture.
• P02AF — Cylinder 6 - Fuel Trim at Min Limit (P02AF): 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, faulty fuel rail pressure sensor or wiring, weak fuel pump or clogged fuel filter.
• P02B0 — Cylinder 6 - Injector Restricted (P02B0): 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 vacuum or intake leaks skewing the mixture, clogged or leaking fuel injectors, faulty fuel pressure regulator.
• P02B1 — OBD2 code P02B1 flags a problem with the fuel delivery and mixture control (cylinder 6 - injector leaking). Short, gentle driving to a shop is usually possible. Common culprits: weak fuel pump or clogged fuel filter, vacuum or intake leaks skewing the mixture, faulty fuel pressure regulator.
• P02B2 — Cylinder 7 - Fuel Trim at Max Limit (P02B2): 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, contaminated or incorrect fuel, faulty fuel pressure regulator.
• P02B3 — Cylinder 7 - Fuel Trim at Min Limit (P02B3): 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, faulty fuel rail pressure sensor or wiring, faulty fuel pressure regulator.