Home / OBD Codes

OBD Code Lookup

Type a code or a symptom — P0300, misfire, catalyst — and find out what it means, how serious it is, and whether it's safe to drive. 170 codes explained in plain words.

No codes match that search. Check the code and try again — codes look like P0300, C1234 or U0100.

P0100Mass Air Flow (MAF) Sensor Circuit ProblemMedium P0101Mass Air Flow (MAF) Sensor — Reading Out of RangeMedium P0102Mass Air Flow (MAF) Sensor — Signal Too LowMedium P0103Mass Air Flow (MAF) Sensor — Signal Too HighMedium P0106Manifold Absolute Pressure (MAP) Sensor — Reading Out of RangeMedium P0107Manifold Absolute Pressure (MAP) Sensor — Signal Too LowMedium P0108Manifold Absolute Pressure (MAP) Sensor — Signal Too HighMedium P0113Intake Air Temperature Sensor — Signal Too HighLow P0115Engine Coolant Temperature Sensor — Circuit ProblemMedium P0117Engine Coolant Temperature Sensor — Signal Too LowMedium P0118Engine Coolant Temperature Sensor — Signal Too HighMedium P0121Throttle Position Sensor — Reading Out of RangeMedium P0122Throttle Position Sensor — Signal Too LowMedium P0123Throttle Position Sensor — Signal Too HighMedium P0128Coolant Thermostat — Engine Running Too CoolLow P0130Oxygen Sensor Circuit Problem (Bank 1, Sensor 1)Medium P0131Oxygen Sensor — Low Voltage (Bank 1, Sensor 1)Medium P0132Oxygen Sensor — High Voltage (Bank 1, Sensor 1)Medium P0133Oxygen Sensor — Slow Response (Bank 1, Sensor 1)Low P0134Oxygen Sensor — No Activity (Bank 1, Sensor 1)Medium P0135Oxygen Sensor Heater Circuit Problem (Bank 1, Sensor 1)Low P0136Oxygen Sensor Circuit Problem (Bank 1, Sensor 2)Low P0137Oxygen Sensor — Low Voltage (Bank 1, Sensor 2)Low P0138Oxygen Sensor — High Voltage (Bank 1, Sensor 2)Low P0140Oxygen Sensor — No Activity (Bank 1, Sensor 2)Low P0141Oxygen Sensor Heater Circuit Problem (Bank 1, Sensor 2)Low P0155Oxygen Sensor Heater Circuit Problem (Bank 2, Sensor 1)Low P0171System Too Lean (Bank 1)Medium P0172System Too Rich (Bank 1)Medium P0174System Too Lean (Bank 2)Medium P0175System Too Rich (Bank 2)Medium P0200Fuel Injector Circuit ProblemHigh P0201Fuel Injector Circuit Problem — Cylinder 1High P0202Fuel Injector Circuit Problem — Cylinder 2High P0219Engine Over-Rev ConditionHigh P0230Fuel Pump Primary Circuit ProblemHigh P0231Fuel Pump Secondary Circuit — Signal Too LowHigh P0300Random / Multiple Cylinder Misfire DetectedHigh P0301Cylinder 1 Misfire DetectedHigh P0302Cylinder 2 Misfire DetectedHigh P0303Cylinder 3 Misfire DetectedHigh P0304Cylinder 4 Misfire DetectedHigh P0305Cylinder 5 Misfire DetectedHigh P0306Cylinder 6 Misfire DetectedHigh P0307Cylinder 7 Misfire DetectedHigh P0308Cylinder 8 Misfire DetectedHigh P0316Engine Misfire Detected on StartupHigh P0325Knock Sensor Circuit Problem (Bank 1)Medium P0327Knock Sensor — Signal Too Low (Bank 1)Medium P0328Knock Sensor — Signal Too High (Bank 1)Medium P0335Crankshaft Position Sensor — Circuit ProblemHigh P0336Crankshaft Position Sensor — Reading Out of RangeHigh P0340Camshaft Position Sensor — Circuit Problem (Bank 1)High P0341Camshaft Position Sensor — Reading Out of Range (Bank 1)High P0342Camshaft Position Sensor — Signal Too Low (Bank 1)High P0343Camshaft Position Sensor — Signal Too High (Bank 1)High P0351Ignition Coil Circuit Problem — Cylinder 1High P0352Ignition Coil Circuit Problem — Cylinder 2High P0353Ignition Coil Circuit Problem — Cylinder 3High P0354Ignition Coil Circuit Problem — Cylinder 4High P0355Ignition Coil Circuit Problem — Cylinder 5High P0356Ignition Coil Circuit Problem — Cylinder 6High P0357Ignition Coil Circuit Problem — Cylinder 7High P0358Ignition Coil Circuit Problem — Cylinder 8High P0363Misfire Detected — Fuel Supply DisabledHigh P0380Glow Plug Circuit ProblemMedium P0390Camshaft Position Sensor — Circuit Problem (Bank 2)High P0401Exhaust Gas Recirculation (EGR) — Not Enough FlowMedium P0402Exhaust Gas Recirculation (EGR) — Too Much FlowMedium P0403Exhaust Gas Recirculation (EGR) — Circuit ProblemMedium P0410Secondary Air Injection System ProblemLow P0411Secondary Air Injection — Wrong FlowLow P0420Catalyst System Efficiency Below Threshold (Bank 1)Medium P0421Catalyst Warm-Up Efficiency Below Threshold (Bank 1)Low P0422Main Catalyst Efficiency Below Threshold (Bank 1)Medium P0430Catalyst System Efficiency Below Threshold (Bank 2)Medium P0440Evaporative Emission (EVAP) System ProblemLow P0441Evaporative Emission (EVAP) — Wrong Purge FlowLow P0442Evaporative Emission (EVAP) — Small Leak DetectedLow P0443Evaporative Emission (EVAP) Purge Valve — Circuit ProblemLow P0446Evaporative Emission (EVAP) Vent Valve — Circuit ProblemLow P0449Evaporative Emission (EVAP) Vent Valve — Circuit ProblemLow P0451Evaporative Emission (EVAP) Pressure Sensor — Reading Out of RangeLow P0452Evaporative Emission (EVAP) Pressure Sensor — Signal Too LowLow P0453Evaporative Emission (EVAP) Pressure Sensor — Signal Too HighLow P0455Evaporative Emission (EVAP) — Large Leak DetectedLow P0456Evaporative Emission (EVAP) — Very Small Leak DetectedLow P0457Evaporative Emission (EVAP) — Leak Detected (Fuel Cap Loose or Off)Low P0463Fuel Level Sensor — Signal Too HighLow P0480Cooling Fan Relay — Circuit ProblemHigh P0496Evaporative Emission (EVAP) — High Purge FlowLow P0500Vehicle Speed Sensor ProblemMedium P0505Idle Air Control System ProblemMedium P0506Idle Speed Too LowMedium P0507Idle Speed Too HighMedium P0513Wrong Immobilizer KeyMedium P0520Engine Oil Pressure Sensor — Circuit ProblemHigh P0521Engine Oil Pressure Sensor — Reading Out of RangeHigh P0522Engine Oil Pressure Sensor — Signal Too LowHigh P0524Engine Oil Pressure Too LowHigh P0530Air Conditioning Refrigerant Pressure Sensor — Circuit ProblemLow P0532Air Conditioning Refrigerant Pressure Sensor — Signal Too LowLow P0562System Voltage Too LowMedium P0563System Voltage Too HighMedium P0571Brake Switch Circuit ProblemMedium P0600Serial Communication Link ProblemMedium P0601Engine Computer Memory — Checksum ErrorHigh P0602Engine Computer — Not ProgrammedHigh P0603Engine Computer Memory — Keep-Alive Memory ErrorMedium P0604Engine Computer Memory — RAM ErrorHigh P0605Engine Computer Memory — ROM ErrorHigh P0606Engine Computer Processor FaultHigh P0615Starter Relay — Circuit ProblemMedium P0620Alternator Control — Circuit ProblemMedium P0638Throttle Actuator — Reading Out of RangeHigh P0650Check Engine Light — Circuit ProblemLow P0685Engine Computer Power Relay — Circuit ProblemHigh P0700Transmission Control System ProblemHigh P0705Transmission Range Sensor — Circuit ProblemHigh P0715Transmission Input Speed Sensor — Circuit ProblemHigh P0717Transmission Input Speed Sensor — No SignalHigh P0720Transmission Output Speed Sensor — Circuit ProblemHigh P0730Wrong Gear RatioHigh P0731Wrong Gear Ratio — 1st GearHigh P0732Wrong Gear Ratio — 2nd GearHigh P0733Wrong Gear Ratio — 3rd GearHigh P0734Wrong Gear Ratio — 4th GearHigh P0740Torque Converter Clutch — Circuit ProblemHigh P0741Torque Converter Clutch — Stuck OffMedium P0743Torque Converter Clutch Solenoid — Circuit ProblemMedium P0748Pressure Control Solenoid — Circuit ProblemHigh P0750Shift Solenoid A — Circuit ProblemHigh P0753Shift Solenoid A — Electrical ProblemHigh P0755Shift Solenoid B — Circuit ProblemHigh P0758Shift Solenoid B — Electrical ProblemHigh P0763Shift Solenoid C — Electrical ProblemHigh P0768Shift Solenoid D — Electrical ProblemHigh P0770Shift Solenoid E — Circuit ProblemHigh P0780Shift ProblemHigh P0785Shift Timing Solenoid — Circuit ProblemHigh P0841Transmission Fluid Pressure Sensor — Reading Out of RangeHigh P0845Transmission Fluid Pressure Sensor — Circuit ProblemHigh P0868Transmission Fluid Pressure Too LowHigh P0882Transmission Control Module — Power Input Too LowHigh P0894Transmission Component SlippingHigh P0900Clutch Actuator — Circuit ProblemHigh P0930Clutch Actuator — Circuit Problem (Open)High P0942Hydraulic Pressure Unit ProblemHigh P1101Mass Air Flow Sensor — Out of Range (Manufacturer-Specific)Medium P1131Lack of Oxygen Sensor Switching — Lean (Manufacturer-Specific, Ford)Medium P1151Lack of Oxygen Sensor Switching — Lean (Manufacturer-Specific, Ford)Medium P1233Fuel Pump Driver Module — Circuit Problem (Manufacturer-Specific, Ford)High P1289Cylinder Head Temperature Sensor — Signal Too High (Manufacturer-Specific, Ford)High P1299Cylinder Head Over-Temperature Protection Active (Manufacturer-Specific, Ford)High P1336Crankshaft Position System — Variation Not Learned (Manufacturer-Specific, GM)Medium P1406EGR Valve Position Sensor — Problem (Manufacturer-Specific, GM)Medium P1443Evaporative Emission System — Purge Valve Problem (Manufacturer-Specific, Ford)Low P1450Evaporative Emission System — Unable to Bleed Vacuum (Manufacturer-Specific, Ford)Low C0035Left Front Wheel Speed Sensor — Circuit ProblemMedium C0040Right Front Wheel Speed Sensor — Circuit ProblemMedium C0045Left Rear Wheel Speed Sensor — Circuit ProblemMedium C0050Right Rear Wheel Speed Sensor — Circuit ProblemMedium C0110ABS Pump Motor — Circuit ProblemMedium C0265Electronic Brake Control Module — Relay Circuit ProblemMedium B0001Driver Airbag — Circuit ProblemHigh U0100Lost Communication with Engine ComputerHigh U0101Lost Communication with Transmission ComputerHigh U0121Lost Communication with ABS ModuleMedium U0140Lost Communication with Body Control ModuleMedium U0155Lost Communication with Instrument ClusterMedium

How OBD codes work

Since 1996 every car sold in the US has an OBD-II port. When the computer detects a problem it stores a five-character code: a letter for the system (P = powertrain, C = chassis, B = body, U = network) and four digits. The first digit after the letter tells you if the code is generic (0) or manufacturer-specific (1). The code alone is not a diagnosis — it points to the system to check.

Questions, answered

What is an OBD-II code?

A code your car's computer stores when it detects a problem. P codes are powertrain (engine and transmission), C codes are chassis (ABS, traction control), B codes are body (airbags), and U codes are network communication faults.

How do I read the code on my car?

Use an OBD-II scanner in the port under the dashboard, or have an auto parts store read it free. Then type the code in the box above.

What should I do first when the check engine light comes on?

Note the code and check the severity on its page here. If the light is flashing, or the code is high severity, stop driving and get it checked. If it is low severity, book a check soon and keep driving normally.

Are these code meanings exact?

The codes follow the SAE J2012 standard, and the explanations here are written in plain words from those definitions. Your car may have extra manufacturer-specific codes (P1xxx) — those are listed too.