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.

Check soon 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 7945–7968 of 8256

Most searched first

U3028Control Module A Disable Feedback CircuitCheck soonNetwork & Communication45–120 minutes for initial diagnosisU3028 concerns control module a disable feedback circuit. Learn what this fault indicates and where to begin diagnosis.U3029Control Module A Disable Feedback Circuit LowCheck soonNetwork & Communication45–120 minutes for initial diagnosisU3029 concerns control module a disable feedback circuit low. Learn what this fault indicates and where to begin diagnosis.U302AControl Module A Disable Feedback Circuit HighCheck soonNetwork & Communication45–120 minutes for initial diagnosisU302A concerns control module a disable feedback circuit high. Learn what this fault indicates and where to begin diagnosis.U302BIgnition Output Accessory/On/StartCheck soonNetwork & Communication45–120 minutes for initial diagnosisU302B concerns ignition output accessory/on/start. Learn what this fault indicates and where to begin diagnosis.U302CIgnition Output Off/On/StartCheck soonNetwork & Communication45–120 minutes for initial diagnosisU302C concerns ignition output off/on/start. Learn what this fault indicates and where to begin diagnosis.U302DIgnition Output On/StartCheck soonNetwork & Communication45–120 minutes for initial diagnosisU302D concerns ignition output on/start. Learn what this fault indicates and where to begin diagnosis.U302EIgnition Output OnCheck soonNetwork & Communication45–120 minutes for initial diagnosisU302E concerns ignition output on. Learn what this fault indicates and where to begin diagnosis.U302FIgnition Output AccessoryCheck soonNetwork & Communication45–120 minutes for initial diagnosisU302F concerns ignition output accessory. Learn what this fault indicates and where to begin diagnosis.U3030Ignition Output StartCheck soonNetwork & Communication45–120 minutes for initial diagnosisU3030 concerns ignition output start. Learn what this fault indicates and where to begin diagnosis.U3031Ignition Output OffCheck soonNetwork & Communication45–120 minutes for initial diagnosisU3031 concerns ignition output off. Learn what this fault indicates and where to begin diagnosis.U3032Ignition Output Accessory/OffCheck soonNetwork & Communication45–120 minutes for initial diagnosisU3032 concerns ignition output accessory/off. Learn what this fault indicates and where to begin diagnosis.U3033Control Module Security Certificate Missing/InvalidCheck soonNetwork & Communication45–120 minutes for initial diagnosisU3033 concerns control module security certificate missing/invalid. Learn what this fault indicates and where to begin diagnosis.U3034Communication Authentication Key/Certificate Missing/InvalidCheck soonNetwork & Communication45–120 minutes for initial diagnosisU3034 concerns communication authentication key/certificate missing/invalid. Learn what this fault indicates and where to begin diagnosis.U3035Communication Authentication Signal Invalid DataCheck soonNetwork & Communication45–120 minutes for initial diagnosisU3035 concerns communication authentication signal invalid data. Learn what this fault indicates and where to begin diagnosis.U3036Communication Authentication Signal PerformanceCheck soonNetwork & Communication45–120 minutes for initial diagnosisU3036 concerns communication authentication signal performance. Learn what this fault indicates and where to begin diagnosis.U3500Control Module Input Power A Circuit Range/PerformanceCheck soonNetwork & Communication45–120 minutes for initial diagnosisU3500 concerns control module input power a circuit range/performance. Learn what this fault indicates and where to begin diagnosis.U3501Control Module Input Power A Circuit LowCheck soonNetwork & Communication45–120 minutes for initial diagnosisU3501 concerns control module input power a circuit low. Learn what this fault indicates and where to begin diagnosis.U3502Control Module Input Power A Circuit HighCheck soonNetwork & Communication45–120 minutes for initial diagnosisU3502 concerns control module input power a circuit high. Learn what this fault indicates and where to begin diagnosis.U3503Control Module Input Power A Circuit Intermittent/ErraticCheck soonNetwork & Communication45–120 minutes for initial diagnosisU3503 concerns control module input power a circuit intermittent/erratic. Learn what this fault indicates and where to begin diagnosis.U3504Control Module Input Power B Circuit Range/PerformanceCheck soonNetwork & Communication45–120 minutes for initial diagnosisU3504 concerns control module input power b circuit range/performance. Learn what this fault indicates and where to begin diagnosis.U3505Control Module Input Power B Circuit LowCheck soonNetwork & Communication45–120 minutes for initial diagnosisU3505 concerns control module input power b circuit low. Learn what this fault indicates and where to begin diagnosis.U3506Control Module Input Power B Circuit HighCheck soonNetwork & Communication45–120 minutes for initial diagnosisU3506 concerns control module input power b circuit high. Learn what this fault indicates and where to begin diagnosis.U3507Control Module Input Power B Circuit Intermittent/ErraticCheck soonNetwork & Communication45–120 minutes for initial diagnosisU3507 concerns control module input power b circuit intermittent/erratic. Learn what this fault indicates and where to begin diagnosis.U3508Control Module Input Power C Circuit Range/PerformanceCheck soonNetwork & Communication45–120 minutes for initial diagnosisU3508 concerns control module input power c circuit range/performance. Learn what this fault indicates and where to begin diagnosis.