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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 1–24 of 118

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P0089Fuel Pressure Regulator 1 PerformanceCheck soonFuel System45–120 minutes for initial diagnosisP0089 means Fuel Pressure Regulator 1 Performance. Learn the likely symptoms, causes, safety implications, and a practical diagnostic order.P0093Fuel System Leak Detected — Large LeakUrgentFuel System1–3 hours for initial diagnosisP0093 means Fuel System Leak Detected — Large Leak. Learn the likely symptoms, causes, safety implications, and a practical diagnostic order.P0171System Too Lean Bank 1 - Complete GuideCheck soonFuel System45–120 minutesDiagnose and fix P0171 system too lean code. Understand what causes a lean fuel mixture and how to solve it with our comprehensive guide.P0304Cylinder 4 Misfire Detected - Causes & FixesUrgentEngine Problems30–75 minutesLearn what P0304 means, why cylinder 4 is misfiring, and how to fix it. Complete guide with symptoms, causes, and step-by-step solutions.P0090Fuel Pressure Regulator 1 Control CircuitCheck soonFuel System45–120 minutes for initial diagnosisP0090 means Fuel Pressure Regulator 1 Control Circuit. Learn the likely symptoms, causes, safety implications, and a practical diagnostic order.P0100Mass or Volume Air Flow Circuit MalfunctionCheck soonSensors & Electronics45–120 minutes for initial diagnosisP0100 means Mass or Volume Air Flow Circuit Malfunction. Learn the likely symptoms, common causes, and a safe diagnostic order before replacing parts.P0102Mass Air Flow Sensor Circuit Low InputSensors & ElectronicsFix P0102 MAF low input code. Learn why your mass air flow sensor reads low and how to clean, test, or replace it.P0105Manifold Absolute Pressure/Barometric Pressure Circuit MalfunctionCheck soonSensors & Electronics45–120 minutes for initial diagnosisP0105 means Manifold Absolute Pressure/Barometric Pressure Circuit Malfunction. Learn the likely symptoms, common causes, and a safe diagnostic order before replacing parts.P0106MAP Sensor Range/Performance ProblemSensors & ElectronicsLearn what triggers P0106 MAP sensor range/performance code and how to fix an implausible manifold pressure reading.P0115Engine Coolant Temperature Sensor 1 CircuitCheck soonSensors & Electronics45–120 minutes for initial diagnosisP0115 means Engine Coolant Temperature Sensor 1 Circuit. Learn the likely symptoms, common causes, and a safe diagnostic order before replacing parts.P0120Throttle/Pedal Position Sensor/Switch A CircuitCheck soonSensors & Electronics45–120 minutes for initial diagnosisP0120 means Throttle/Pedal Position Sensor/Switch A Circuit. Learn the likely symptoms, common causes, and a safe diagnostic order before replacing parts.P0121Throttle Position Sensor Range/PerformanceSensors & ElectronicsDiagnose P0121 throttle position sensor circuit range/performance code and get it fixed.P0131O2 Sensor Low Voltage Bank 1 Sensor 1Sensors & ElectronicsDiagnose P0131 oxygen sensor low voltage code. Learn why the upstream O2 sensor is reading low and how to fix it.P0133O2 Sensor Slow Response Bank 1 Sensor 1Sensors & ElectronicsFix P0133 slow responding oxygen sensor. Learn why the O2 sensor is responding slowly and repair options.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.P0174System Too Lean Bank 2 - Causes & SolutionsFuel SystemFix P0174 lean condition on Bank 2. Often appears with P0171. Learn the common causes and effective repair strategies.P0190Fuel Rail Pressure Sensor A CircuitCheck soonFuel System45–120 minutes for initial diagnosisP0190 means Fuel Rail Pressure Sensor A Circuit. Learn the likely symptoms, common causes, and a safe diagnostic order before replacing parts.P0200Injector Circuit/OpenCheck soonFuel System45–120 minutes for initial diagnosisP0200 means Injector Circuit/Open. Learn the likely symptoms, common causes, and a safe diagnostic order before replacing parts.P0201Injector Circuit Malfunction Cylinder 1Fuel SystemDiagnose P0201 fuel injector circuit fault on cylinder 1 - wiring, driver, and injector causes plus fixes.P0207Injector Circuit/Open Cylinder 7Check soonFuel System45–120 minutes for initial diagnosisP0207 means Injector Circuit/Open Cylinder 7. Learn the likely symptoms, causes, safety implications, and a practical diagnostic order.P0234Turbocharger/Supercharger A Overboost ConditionUrgentEngine Problems1–3 hours for initial diagnosisP0234 means Turbocharger/Supercharger A Overboost Condition. Learn the likely symptoms, common causes, and a safe diagnostic order before replacing parts.P0299Turbocharger/Supercharger Underboost ConditionEngine ProblemsFix P0299 turbo underboost code. Learn why your turbo isn't making enough boost and how to diagnose the cause.