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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 1441–1464 of 7353

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P0641Sensor Reference Voltage A Circuit/OpenCheck soonElectrical & Charging System30–120 minutes for initial diagnosisP0641 relates to sensor reference voltage a circuit/open. Check the fault conditions and vehicle-specific procedure before replacing parts.P0642Sensor Reference Voltage A Circuit LowCheck soonElectrical & Charging System30–120 minutes for initial diagnosisP0642 relates to sensor reference voltage a circuit low. Check the fault conditions and vehicle-specific procedure before replacing parts.P0643Sensor Reference Voltage A Circuit HighCheck soonElectrical & Charging System30–120 minutes for initial diagnosisP0643 relates to sensor reference voltage a circuit high. Check the fault conditions and vehicle-specific procedure before replacing parts.P0644Driver Display Serial Communication CircuitCheck soonSensors & Electronics30–120 minutes for initial diagnosisP0644 relates to driver display serial communication circuit. Check the fault conditions and vehicle-specific procedure before replacing parts.P0645A/C Clutch Relay Control CircuitLow priorityTransmission Issues30–120 minutes for initial diagnosisP0645 relates to a/c clutch relay control circuit. Check the fault conditions and vehicle-specific procedure before replacing parts.P0646A/C Clutch Relay Control Circuit LowLow priorityTransmission Issues30–120 minutes for initial diagnosisP0646 relates to a/c clutch relay control circuit low. Check the fault conditions and vehicle-specific procedure before replacing parts.P0647A/C Clutch Relay Control Circuit HighLow priorityTransmission Issues30–120 minutes for initial diagnosisP0647 relates to a/c clutch relay control circuit high. Check the fault conditions and vehicle-specific procedure before replacing parts.P0648Immobilizer Lamp Control CircuitCheck soonSensors & Electronics30–120 minutes for initial diagnosisP0648 relates to immobilizer lamp control circuit. Check the fault conditions and vehicle-specific procedure before replacing parts.P0649Speed Control Lamp Control CircuitCheck soonSensors & Electronics30–120 minutes for initial diagnosisP0649 relates to speed control lamp control circuit. Check the fault conditions and vehicle-specific procedure before replacing parts.P064AFuel Pump Control Module ACheck soonFuel System30–120 minutes for initial diagnosisP064A relates to fuel pump control module a. Check the fault conditions and vehicle-specific procedure before replacing parts.P064BPTO Control ModuleCheck soonSensors & Electronics30–120 minutes for initial diagnosisP064B relates to pto control module. Check the fault conditions and vehicle-specific procedure before replacing parts.P064CGlow Plug Control Module 1Check soonSensors & Electronics30–120 minutes for initial diagnosisP064C relates to glow plug control module 1. Check the fault conditions and vehicle-specific procedure before replacing parts.P064DInternal Control Module O2 Sensor Processor Performance Bank 1Check soonSensors & Electronics30–120 minutes for initial diagnosisP064D relates to internal control module o2 sensor processor performance bank 1. Check the fault conditions and vehicle-specific procedure before replacing parts.P064EInternal Control Module O2 Sensor Processor Performance Bank 2Check soonSensors & Electronics30–120 minutes for initial diagnosisP064E relates to internal control module o2 sensor processor performance bank 2. Check the fault conditions and vehicle-specific procedure before replacing parts.P064FUnauthorized Software/Calibration DetectedCheck soonSensors & Electronics30–120 minutes for initial diagnosisP064F relates to unauthorized software/calibration detected. Check the fault conditions and vehicle-specific procedure before replacing parts.P0650MIL Control Circuit/OpenCheck soonSensors & Electronics30–120 minutes for initial diagnosisP0650 relates to mil control circuit/open. Check the fault conditions and vehicle-specific procedure before replacing parts.P0651Sensor Reference Voltage B Circuit/OpenCheck soonElectrical & Charging System30–120 minutes for initial diagnosisP0651 relates to sensor reference voltage b circuit/open. Check the fault conditions and vehicle-specific procedure before replacing parts.P0652Sensor Reference Voltage B Circuit LowCheck soonElectrical & Charging System30–120 minutes for initial diagnosisP0652 relates to sensor reference voltage b circuit low. Check the fault conditions and vehicle-specific procedure before replacing parts.P0653Sensor Reference Voltage B Circuit HighCheck soonElectrical & Charging System30–120 minutes for initial diagnosisP0653 relates to sensor reference voltage b circuit high. Check the fault conditions and vehicle-specific procedure before replacing parts.P0654Engine RPM Output Circuit/OpenCheck soonSensors & Electronics30–120 minutes for initial diagnosisP0654 relates to engine rpm output circuit/open. Check the fault conditions and vehicle-specific procedure before replacing parts.P0655Engine Hot Lamp Output Control CircuitCheck soonSensors & Electronics30–120 minutes for initial diagnosisP0655 relates to engine hot lamp output control circuit. Check the fault conditions and vehicle-specific procedure before replacing parts.P0656Fuel Level Output CircuitCheck soonFuel System30–120 minutes for initial diagnosisP0656 relates to fuel level output circuit. Check the fault conditions and vehicle-specific procedure before replacing parts.P0657Actuator Supply Voltage A Circuit/OpenCheck soonElectrical & Charging System30–120 minutes for initial diagnosisP0657 relates to actuator supply voltage a circuit/open. Check the fault conditions and vehicle-specific procedure before replacing parts.P0658Actuator Supply Voltage A Circuit LowCheck soonElectrical & Charging System30–120 minutes for initial diagnosisP0658 relates to actuator supply voltage a circuit low. Check the fault conditions and vehicle-specific procedure before replacing parts.