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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 1009–1032 of 7353

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P048AExhaust Pressure Control Valve A Stuck ClosedCheck soonSensors & Electronics30–120 minutes for initial diagnosisP048A relates to exhaust pressure control valve a stuck closed. Check the fault conditions and vehicle-specific procedure before replacing parts.P048BExhaust Pressure Control Valve A Position Sensor/Switch CircuitCheck soonSensors & Electronics30–120 minutes for initial diagnosisP048B relates to exhaust pressure control valve a position sensor/switch circuit. Check the fault conditions and vehicle-specific procedure before replacing parts.P048CExhaust Pressure Control Valve A Position Sensor/Switch Circuit Range/PerformanceCheck soonSensors & Electronics30–120 minutes for initial diagnosisP048C relates to exhaust pressure control valve a position sensor/switch circuit range/performance. Check the fault conditions and vehicle-specific procedure before replacing parts.P048DExhaust Pressure Control Valve A Position Sensor/Switch Circuit LowCheck soonSensors & Electronics30–120 minutes for initial diagnosisP048D relates to exhaust pressure control valve a position sensor/switch circuit low. Check the fault conditions and vehicle-specific procedure before replacing parts.P048EExhaust Pressure Control Valve A Position Sensor/Switch Circuit HighCheck soonSensors & Electronics30–120 minutes for initial diagnosisP048E relates to exhaust pressure control valve a position sensor/switch circuit high. Check the fault conditions and vehicle-specific procedure before replacing parts.P048FExhaust Pressure Control Valve A Position Sensor/Switch Circuit Intermittent/ErraticCheck soonSensors & Electronics30–120 minutes for initial diagnosisP048F relates to exhaust pressure control valve a position sensor/switch circuit intermittent/erratic. Check the fault conditions and vehicle-specific procedure before replacing parts.P0490EGR A Control Circuit HighCheck soonEmissions System30–120 minutes for initial diagnosisP0490 relates to egr a control circuit high. Check the fault conditions and vehicle-specific procedure before replacing parts.P0491AIR System Insufficient Flow Bank 1Check soonSensors & Electronics30–120 minutes for initial diagnosisP0491 relates to air system insufficient flow bank 1. Check the fault conditions and vehicle-specific procedure before replacing parts.P0492AIR System Insufficient Flow Bank 2Check soonSensors & Electronics30–120 minutes for initial diagnosisP0492 relates to air system insufficient flow bank 2. Check the fault conditions and vehicle-specific procedure before replacing parts.P0493Fan OverspeedUrgentEngine Problems30–120 minutes for initial diagnosisP0493 relates to fan overspeed. Check the fault conditions and vehicle-specific procedure before replacing parts.P0494Fan 1 UnderspeedCheck soonEngine Problems30–120 minutes for initial diagnosisP0494 relates to fan 1 underspeed. Check the fault conditions and vehicle-specific procedure before replacing parts.P0495Fan 1 OverspeedUrgentEngine Problems30–120 minutes for initial diagnosisP0495 relates to fan 1 overspeed. Check the fault conditions and vehicle-specific procedure before replacing parts.P0496Evaporative Emission System High Purge FlowLow priorityEmissions System30–120 minutes for initial diagnosisP0496 indicates a fault related to evaporative emission system high purge flow. Learn the likely causes and a practical diagnostic order before replacing parts.P0497Evaporative Emission System Low Purge FlowLow priorityEmissions System30–120 minutes for initial diagnosisP0497 indicates a fault related to evaporative emission system low purge flow. Learn the likely causes and a practical diagnostic order before replacing parts.P0498Evaporative Emission System Vent Valve Control Circuit LowLow priorityEmissions System30–120 minutes for initial diagnosisP0498 indicates a fault related to evaporative emission system vent valve control circuit low. Learn the likely causes and a practical diagnostic order before replacing parts.P0499Evaporative Emission System Vent Valve Control Circuit HighLow priorityEmissions System30–120 minutes for initial diagnosisP0499 indicates a fault related to evaporative emission system vent valve control circuit high. Learn the likely causes and a practical diagnostic order before replacing parts.P049AEGR B FlowCheck soonEmissions System30–120 minutes for initial diagnosisP049A relates to egr b flow. Check the fault conditions and vehicle-specific procedure before replacing parts.P049BEGR B Flow Insufficient DetectedCheck soonEmissions System30–120 minutes for initial diagnosisP049B relates to egr b flow insufficient detected. Check the fault conditions and vehicle-specific procedure before replacing parts.P049CEGR B Flow Excessive DetectedCheck soonEmissions System30–120 minutes for initial diagnosisP049C relates to egr b flow excessive detected. Check the fault conditions and vehicle-specific procedure before replacing parts.P049DEGR A Control Position Exceeded Learning LimitCheck soonEmissions System30–120 minutes for initial diagnosisP049D relates to egr a control position exceeded learning limit. Check the fault conditions and vehicle-specific procedure before replacing parts.P049EEGR B Control Position Exceeded Learning LimitCheck soonEmissions System30–120 minutes for initial diagnosisP049E relates to egr b control position exceeded learning limit. Check the fault conditions and vehicle-specific procedure before replacing parts.P049FExhaust Pressure Control Valve BCheck soonSensors & Electronics30–120 minutes for initial diagnosisP049F relates to exhaust pressure control valve b. Check the fault conditions and vehicle-specific procedure before replacing parts.P04A0Exhaust Pressure Control Valve B Range/PerformanceCheck soonSensors & Electronics30–120 minutes for initial diagnosisP04A0 relates to exhaust pressure control valve b range/performance. Check the fault conditions and vehicle-specific procedure before replacing parts.P04A1Exhaust Pressure Control Valve B LowCheck soonSensors & Electronics30–120 minutes for initial diagnosisP04A1 relates to exhaust pressure control valve b low. Check the fault conditions and vehicle-specific procedure before replacing parts.