Diagnostic library

Find an OBD2 code

Search the code from your scanner, then narrow the library by system, severity, or code family.

9,253 diagnostic guides

Sort

Find codes by symptomChoose what you notice to search matching code guides.

Rough idle or shakingVibration while stopped Hard to startLong cranking or no-start Engine stallsCuts out at idle or on the road Hesitates or loses powerSlow response when accelerating Battery light is onCharging system warning Harsh gear changesDelayed or rough shifting

A symptom can have several causes. Treat matching codes as clues and follow the diagnostic checks in each guide.

Low priority Clear all

Quick browse

Choose a vehicle system

Engine1049 Emissions515 Fuel1016 Sensors & Electronics2110 Transmission866 Electrical & Charging1797 Body & Restraints193 Chassis & Brakes479 Network & Communication1228

FiltersSeverity · family

Severity

All severities9253 Low priority305 Check soon8256 Urgent621

Code family

All families9253 P · Powertrain7353 B · Body193 C · Chassis479 U · Network1228

Vehicle coverage

These are generic OBD2 definitions. Exact make, model, engine, and year compatibility will appear after vehicle-fitment data is added.

Diagnostic codes

Showing 25–48 of 305

Most searched first

P00D1HO2S Heater Control Circuit Range/Performance Bank 1 Sensor 1Low prioritySensors & Electronics30–120 minutes for initial diagnosisP00D1 relates to ho2s heater control circuit range/performance bank 1 sensor 1. Check the fault conditions and vehicle-specific procedure before replacing parts.P00D2HO2S Heater Control Circuit Range/Performance Bank 1 Sensor 2Low prioritySensors & Electronics30–120 minutes for initial diagnosisP00D2 relates to ho2s heater control circuit range/performance bank 1 sensor 2. Check the fault conditions and vehicle-specific procedure before replacing parts.P00D3HO2S Heater Control Circuit Range/Performance Bank 2 Sensor 1Low prioritySensors & Electronics30–120 minutes for initial diagnosisP00D3 relates to ho2s heater control circuit range/performance bank 2 sensor 1. Check the fault conditions and vehicle-specific procedure before replacing parts.P00D4HO2S Heater Control Circuit Range/Performance Bank 2 Sensor 2Low prioritySensors & Electronics30–120 minutes for initial diagnosisP00D4 relates to ho2s heater control circuit range/performance bank 2 sensor 2. Check the fault conditions and vehicle-specific procedure before replacing parts.P00D9Ambient Air Temperature Sensor Circuit BLow prioritySensors & Electronics30–120 minutes for initial diagnosisP00D9 relates to ambient air temperature sensor circuit b. Check the fault conditions and vehicle-specific procedure before replacing parts.P00DAAmbient Air Temperature Sensor Circuit B Range/PerformanceLow prioritySensors & Electronics30–120 minutes for initial diagnosisP00DA relates to ambient air temperature sensor circuit b range/performance. Check the fault conditions and vehicle-specific procedure before replacing parts.P00DBAmbient Air Temperature Sensor Circuit B LowLow prioritySensors & Electronics30–120 minutes for initial diagnosisP00DB relates to ambient air temperature sensor circuit b low. Check the fault conditions and vehicle-specific procedure before replacing parts.P00DCAmbient Air Temperature Sensor Circuit B HighLow prioritySensors & Electronics30–120 minutes for initial diagnosisP00DC relates to ambient air temperature sensor circuit b high. Check the fault conditions and vehicle-specific procedure before replacing parts.P00DDAmbient Air Temperature Sensor Circuit B Intermittent/ErraticLow prioritySensors & Electronics30–120 minutes for initial diagnosisP00DD relates to ambient air temperature sensor circuit b intermittent/erratic. Check the fault conditions and vehicle-specific procedure before replacing parts.P00FEEVAP System Tank Vapor Line Restricted/BlockedLow priorityEmissions System30–120 minutes for initial diagnosisP00FE relates to evap system tank vapor line restricted/blocked. Check the fault conditions and vehicle-specific procedure before replacing parts.P0136Oxygen Sensor Circuit Bank 1 Sensor 2Low prioritySensors & Electronics30–90 minutes for initial diagnosisP0136 means Oxygen Sensor Circuit Bank 1 Sensor 2. Learn the likely symptoms, common causes, and a safe diagnostic order before replacing parts.P0140Oxygen Sensor Circuit No Activity Detected Bank 1 Sensor 2Low prioritySensors & Electronics30–90 minutes for initial diagnosisP0140 means Oxygen Sensor Circuit No Activity Detected Bank 1 Sensor 2. Learn the likely symptoms, common causes, and a safe diagnostic order before replacing parts.P0150Oxygen Sensor Circuit Bank 2 Sensor 1Low prioritySensors & Electronics30–90 minutes for initial diagnosisP0150 means Oxygen Sensor Circuit Bank 2 Sensor 1. Learn the likely symptoms, common causes, and a safe diagnostic order before replacing parts.P017FEVAP System Leak Detection Pump Module Air Filter RestrictedLow priorityEmissions System30–120 minutes for initial diagnosisP017F relates to evap system leak detection pump module air filter restricted. Check the fault conditions and vehicle-specific procedure before replacing parts.P0400Exhaust Gas Recirculation Flow MalfunctionLow priorityEmissions System30–90 minutes for initial diagnosisP0400 means Exhaust Gas Recirculation Flow Malfunction. Learn the likely symptoms, common causes, and a safe diagnostic order before replacing parts.P0411Secondary Air Injection System Incorrect Flow DetectedLow priorityEmissions System30–90 minutes for initial diagnosisP0411 means Secondary Air Injection System Incorrect Flow Detected. Learn the likely symptoms, common causes, and a safe diagnostic order before replacing parts.P0422Main Catalyst Efficiency Below Threshold (Bank 1)Low priorityEmissions System30–90 minutes for initial diagnosisP0422 indicates the catalyst monitor reports that main-catalyst efficiency on Bank 1 is below the calibrated threshold. Learn what to inspect before replacing parts.P0423Heated Catalyst Efficiency Below Threshold (Bank 1)Low priorityEmissions System30–90 minutes for initial diagnosisP0423 indicates the heated-catalyst monitor reports efficiency below the calibrated threshold on Bank 1. Learn what to inspect before replacing parts.P0431Warm Up Catalyst Efficiency Below Threshold Bank 2Low priorityEmissions System30–120 minutes for initial diagnosisP0431 indicates a fault related to warm up catalyst efficiency below threshold bank 2. Learn the likely causes and a practical diagnostic order before replacing parts.P0432Main Catalyst Efficiency Below Threshold (Bank 2)Low priorityEmissions System30–90 minutes for initial diagnosisP0432 indicates the catalyst monitor reports that main-catalyst efficiency on Bank 2 is below the calibrated threshold. Learn what to inspect before replacing parts.P0433Heated Catalyst Efficiency Below Threshold (Bank 2)Low priorityEmissions System30–90 minutes for initial diagnosisP0433 indicates the heated-catalyst monitor reports efficiency below the calibrated threshold on Bank 2. Learn what to inspect before replacing parts.P043EEVAP System Leak Detection Reference Orifice Low FlowLow priorityEmissions System30–120 minutes for initial diagnosisP043E relates to evap system leak detection reference orifice low flow. Check the fault conditions and vehicle-specific procedure before replacing parts.P043FEVAP System Leak Detection Reference Orifice High FlowLow priorityEmissions System30–120 minutes for initial diagnosisP043F relates to evap system leak detection reference orifice high flow. Check the fault conditions and vehicle-specific procedure before replacing parts.P0441Evaporative Emission System Incorrect Purge FlowLow priorityEmissions System30–90 minutes for initial diagnosisP0441 means Evaporative Emission System Incorrect Purge Flow. Learn the likely symptoms, common causes, and a safe diagnostic order before replacing parts.