Network Codes
1,532 OBD-II diagnostic trouble codes in this category.
Showing page 15 of 16 (1,532 codes total)
| Code | Description | Subsystem | Severity |
|---|---|---|---|
| U302A | Control Module A Disable Feedback Circuit High | Network Communication | Medium |
| U302B | Ignition Output Accessory/On/Start | Network Communication | Medium |
| U302C | Ignition Output Off/On/Start | Network Communication | Medium |
| U302D | Ignition Output On/Start | Network Communication | Medium |
| U302E | Ignition Output On | Network Communication | Medium |
| U302F | Ignition Output Accessory | Network Communication | Medium |
| U3030 | Ignition Output Start | Network Communication | Medium |
| U3031 | Ignition Output Off | Network Communication | Medium |
| U3032 | Ignition Output Accessory/Off | Network Communication | Medium |
| U3033 | Control Module Security Certificate Missing/Invalid | Network Communication | Medium |
| U3034 | Communication Authentication Key/Certificate Missing/Invalid | CAN Bus | High |
| U3035 | Communication Authentication Signal Invalid Data | Data Integrity | High |
| U3036 | Communication Authentication Signal Performance | CAN Bus | High |
| U3500 | Control Module Input Power A Circuit Range/Performance | Network Communication | Medium |
| U3501 | Control Module Input Power A Circuit Low | Network Communication | Medium |
| U3502 | Control Module Input Power A Circuit High | Network Communication | Medium |
| U3503 | Control Module Input Power A Circuit Intermittent/Erratic | Network Communication | Medium |
| U3504 | Control Module Input Power B Circuit Range/Performance | Network Communication | Medium |
| U3505 | Control Module Input Power B Circuit Low | Network Communication | Medium |
| U3506 | Control Module Input Power B Circuit High | Network Communication | Medium |
| U3507 | Control Module Input Power B Circuit Intermittent/Erratic | Network Communication | Medium |
| U3508 | Control Module Input Power C Circuit Range/Performance | Network Communication | Medium |
| U3509 | Control Module Input Power C Circuit Low | Network Communication | Medium |
| U350A | Control Module Input Power C Circuit High | Network Communication | Medium |
| U350B | Control Module Input Power C Circuit Intermittent/Erratic | Network Communication | Medium |
| U350C | Control Module Cooling Fan Circuit/Open | Network Communication | Medium |
| U350D | Control Module Cooling Fan Circuit Low | Network Communication | Medium |
| U350E | Control Module Cooling Fan Circuit High | Network Communication | Medium |
| U350F | Control Module Cooling Fan Circuit Range/Performance | Network Communication | Medium |
| U3510 | Control Module Missing Calibration | Network Communication | Medium |
| U3511 | High Voltage System Interlock Circuit B | Network Communication | Medium |
| U3512 | High Voltage System Interlock Circuit B Performance | Network Communication | Medium |
| U3513 | High Voltage System Interlock Circuit B Low | Network Communication | Medium |
| U3514 | High Voltage System Interlock Circuit B High | Network Communication | Medium |
| U3515 | High Voltage System Interlock Circuit C | Network Communication | Medium |
| U3516 | High Voltage System Interlock Circuit C Performance | Network Communication | Medium |
| U3517 | High Voltage System Interlock Circuit C Low | Network Communication | Medium |
| U3518 | High Voltage System Interlock Circuit C High | Network Communication | Medium |
| U3519 | High Voltage System Interlock Circuit D | Network Communication | Medium |
| U351A | High Voltage System Interlock Circuit D Performance | Network Communication | Medium |
| U351B | High Voltage System Interlock Circuit D Low | Network Communication | Medium |
| U351C | High Voltage System Interlock Circuit D High | Network Communication | Medium |
| U351D | High Voltage System Interlock Circuit E | Network Communication | Medium |
| U351E | High Voltage System Interlock Circuit E Performance | Network Communication | Medium |
| U351F | High Voltage System Interlock Circuit E Low | Network Communication | Medium |
| U3520 | High Voltage System Interlock Circuit E High | Network Communication | Medium |
| U3521 | High Voltage System Interlock Circuit F | Network Communication | Medium |
| U3522 | High Voltage System Interlock Circuit F Performance | Network Communication | Medium |
| U3523 | High Voltage System Interlock Circuit F Low | Network Communication | Medium |
| U3524 | High Voltage System Interlock Circuit F High | Network Communication | Medium |
| U3525 | High Voltage System Interlock Circuit G | Network Communication | Medium |
| U3526 | High Voltage System Interlock Circuit G Performance | Network Communication | Medium |
| U3527 | High Voltage System Interlock Circuit G Low | Network Communication | Medium |
| U3528 | High Voltage System Interlock Circuit G High | Network Communication | Medium |
| U3529 | High Voltage System Interlock Circuit H | Network Communication | Medium |
| U352A | High Voltage System Interlock Circuit H Performance | Network Communication | Medium |
| U352B | High Voltage System Interlock Circuit H Low | Network Communication | Medium |
| U352C | High Voltage System Interlock Circuit H High | Network Communication | Medium |
| U352D | High Voltage System Interlock Circuit J | Network Communication | Medium |
| U352E | High Voltage System Interlock Circuit J Performance | Network Communication | Medium |
| U352F | High Voltage System Interlock Circuit J Low | Network Communication | Medium |
| U3530 | High Voltage System Interlock Circuit J High | Network Communication | Medium |
| U3531 | High Voltage System Interlock Circuit K | Network Communication | Medium |
| U3532 | High Voltage System Interlock Circuit K Performance | Network Communication | Medium |
| U3533 | High Voltage System Interlock Circuit K Low | Network Communication | Medium |
| U3534 | High Voltage System Interlock Circuit K High | Network Communication | Medium |
| U3535 | High Voltage System Interlock Circuit L | Network Communication | Medium |
| U3536 | High Voltage System Interlock Circuit L Performance | Network Communication | Medium |
| U3537 | High Voltage System Interlock Circuit L Low | Network Communication | Medium |
| U3538 | High Voltage System Interlock Circuit L High | Network Communication | Medium |
| U3539 | High Voltage System Interlock Circuit M | Network Communication | Medium |
| U353A | High Voltage System Interlock Circuit M Performance | Network Communication | Medium |
| U353B | High Voltage System Interlock Circuit M Low | Network Communication | Medium |
| U353C | High Voltage System Interlock Circuit M High | Network Communication | Medium |
| U353D | High Voltage System Interlock Circuit N | Network Communication | Medium |
| U353E | High Voltage System Interlock Circuit N Performance | Network Communication | Medium |
| U353F | High Voltage System Interlock Circuit N Low | Network Communication | Medium |
| U3540 | High Voltage System Interlock Circuit N High | Network Communication | Medium |
| U3541 | High Voltage System Interlock Circuit O | Network Communication | Medium |
| U3542 | High Voltage System Interlock Circuit O Performance | Network Communication | Medium |
| U3543 | High Voltage System Interlock Circuit O Low | Network Communication | Medium |
| U3544 | High Voltage System Interlock Circuit O High | Network Communication | Medium |
| U3545 | High Voltage System Interlock Circuit P | Network Communication | Medium |
| U3546 | High Voltage System Interlock Circuit P Performance | Network Communication | Medium |
| U3547 | High Voltage System Interlock Circuit P Low | Network Communication | Medium |
| U3548 | High Voltage System Interlock Circuit P High | Network Communication | Medium |
| U3549 | Hydrogen Tank High Pressure Sensor 1 Circuit | Network Communication | Medium |
| U354A | Hydrogen Tank A Temperature Sensor 1 Circuit | Network Communication | Medium |
| U354B | Hydrogen Tank A Temperature Sensor 2 Circuit | Network Communication | Medium |
| U354C | Hydrogen Tank B Temperature Sensor 1 Circuit | Network Communication | Medium |
| U354D | Hydrogen Tank B Temperature Sensor 2 Circuit | Network Communication | Medium |
| U354E | Hydrogen Tank C Temperature Sensor 1 Circuit | Network Communication | Medium |
| U354F | Hydrogen Tank C Temperature Sensor 2 Circuit | Network Communication | Medium |
| U3550 | Hydrogen Tank A Valve Control Circuit | Network Communication | Medium |
| U3551 | Hydrogen Tank A Valve Enable Circuit | Network Communication | Medium |
| U3552 | Hydrogen Tank A Valve Performance | Network Communication | Medium |
| U3553 | Hydrogen Tank B Valve Control Circuit | Network Communication | Medium |
| U3554 | Hydrogen Tank B Valve Enable Circuit | Network Communication | Medium |
| U3555 | Hydrogen Tank B Valve Performance | Network Communication | Medium |
| U3556 | Hydrogen Tank C Valve Control Circuit | Network Communication | Medium |
About Network Codes
This page lists all 1,532 OBD-II diagnostic trouble codes classified under the Network category. These codes are stored by your vehicle's onboard computer when a sensor detects a malfunction in the network system. Each code begins with a letter indicating the system (P for Powertrain, B for Body, C for Chassis, U for Network) followed by four digits that identify the specific fault.
When your check engine light comes on, an OBD-II scanner reads these stored codes to help pinpoint the problem. Generic codes (where the second digit is 0) follow the SAE J2012 standard and mean the same thing on every vehicle. Manufacturer-specific codes (where the second digit is 1) may have different meanings depending on the vehicle brand.
Click any code in the table above to see its full description, possible causes, common symptoms, and step-by-step repair guidance. Use the search box to quickly find a specific code within this category.