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9,253 diagnostic guides

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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.

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

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All severities9253 Low priority305 Check soon8256 Urgent621

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

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

Diagnostic codes

Showing 505–515 of 515

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P0406Exhaust Gas Recirculation Sensor A Circuit HighLow priorityEmissions System30–90 minutes for initial diagnosisP0406 means Exhaust Gas Recirculation Sensor A Circuit High. Learn the likely symptoms, common causes, and a safe diagnostic order before replacing parts.P0410Secondary Air Injection System MalfunctionEmissions SystemDiagnose P0410 secondary air injection (AIR) system code - common causes and how to fix it.P0412Secondary Air Injection System Switching Valve A Circuit MalfunctionLow priorityEmissions System30–90 minutes for initial diagnosisP0412 means Secondary Air Injection System Switching Valve A Circuit Malfunction. Learn the likely symptoms, common causes, and a safe diagnostic order before replacing parts.P0413Secondary Air Injection System Switching Valve A Circuit OpenLow priorityEmissions System30–90 minutes for initial diagnosisP0413 means Secondary Air Injection System Switching Valve A Circuit Open. Learn the likely symptoms, common causes, and a safe diagnostic order before replacing parts.P0414Secondary Air Injection System Switching Valve A Circuit ShortedLow priorityEmissions System30–90 minutes for initial diagnosisP0414 means Secondary Air Injection System Switching Valve A Circuit Shorted. Learn the likely symptoms, common causes, and a safe diagnostic order before replacing parts.P0421Warm Up Catalyst Efficiency Below Threshold Bank 1Emissions SystemUnderstand P0421 catalyst code. Learn about warm-up catalyst monitoring and efficiency testing.P0443EVAP Purge Control Valve Circuit MalfunctionEmissions SystemFix the P0443 EVAP purge valve circuit code, a common electrical fault in the evaporative emissions system.P0446EVAP Vent Control Circuit MalfunctionEmissions SystemDiagnose P0446 EVAP vent valve code. Learn about the vent control valve and how to fix circuit problems.P0449EVAP Vent Valve/Solenoid Circuit MalfunctionEmissions SystemFix P0449 EVAP vent solenoid circuit code - a common and inexpensive fix for check engine light issues.P0451EVAP Pressure Sensor Range/PerformanceEmissions SystemUnderstand P0451 EVAP pressure sensor range/performance code and how to diagnose it.P0452EVAP Pressure Sensor Low InputEmissions SystemFix P0452 EVAP pressure sensor low input code - causes and step-by-step diagnosis.