Diagnostic knowledge / C056D — Electronic Control Unit Hardware; Electronic Control Unit Hardware Signal Erratic; Electronic Control Unit Hardware Low Signal Amplitude; Electronic Control Unit Hardware Internal Checksum Error; Electronic Control Unit Hardware General Memory Malfunction; Electronic Control Unit Hardware Special Memory Malfunction; Electronic Control Unit Hardware RAM Malfunction; Electronic Control Unit Hardware ROM Malfunction; Electronic Control Unit Hardware EEPROM Performance/Malfunction; Electronic Control Unit Hardware Software Malfunction; Electronic Control Unit Hardware Internal Malfunction; Electronic Control Unit Hardware Incorrect Component Installed; Electronic Control Unit Hardware Self-Test Malfunction; Electronic Control Unit Hardware Internal Communication Malfunction; Electronic Control Unit Hardware EEPROM Incorrect Programming
C056D
Electronic Control Unit Hardware; Electronic Control Unit Hardware Signal Erratic; Electronic Control Unit Hardware Low Signal Amplitude; Electronic Control Unit Hardware Internal Checksum Error; Electronic Control Unit Hardware General Memory Malfunction; Electronic Control Unit Hardware Special Memory Malfunction; Electronic Control Unit Hardware RAM Malfunction; Electronic Control Unit Hardware ROM Malfunction; Electronic Control Unit Hardware EEPROM Performance/Malfunction; Electronic Control Unit Hardware Software Malfunction; Electronic Control Unit Hardware Internal Malfunction; Electronic Control Unit Hardware Incorrect Component Installed; Electronic Control Unit Hardware Self-Test Malfunction; Electronic Control Unit Hardware Internal Communication Malfunction; Electronic Control Unit Hardware EEPROM Incorrect Programming
C056D is described as “Electronic Control Unit Hardware; Electronic Control Unit Hardware Signal Erratic; Electronic Control Unit Hardware Low Signal Amplitude; Electronic Control Unit Hardware Internal Checksum Error; Electronic Control Unit Hardware General Memory Malfunction; Electronic Control Unit Hardware Special Memory Malfunction; Electronic Control Unit Hardware RAM Malfunction; Electronic Control Unit Hardware ROM Malfunction; Electronic Control Unit Hardware EEPROM Performance/Malfunction; Electronic Control Unit Hardware Software Malfunction; Electronic Control Unit Hardware Internal Malfunction; Electronic Control Unit Hardware Incorrect Component Installed; Electronic Control Unit Hardware Self-Test Malfunction; Electronic Control Unit Hardware Internal Communication Malfunction; Electronic Control Unit Hardware EEPROM Incorrect Programming” in the GM reference.
Manufacturer reference family
GM: C056D
enElectronic Control Unit Hardware; Electronic Control Unit Hardware Signal Erratic; Electronic Control Unit Hardware Low Signal Amplitude; Electronic Control Unit Hardware Internal Checksum Error; Electronic Control Unit Hardware General Memory Malfunction; Electronic Control Unit Hardware Special Memory Malfunction; Electronic Control Unit Hardware RAM Malfunction; Electronic Control Unit Hardware ROM Malfunction; Electronic Control Unit Hardware EEPROM Performance/Malfunction; Electronic Control Unit Hardware Software Malfunction; Electronic Control Unit Hardware Internal Malfunction; Electronic Control Unit Hardware Incorrect Component Installed; Electronic Control Unit Hardware Self-Test Malfunction; Electronic Control Unit Hardware Internal Communication Malfunction; Electronic Control Unit Hardware EEPROM Incorrect Programming
- Reference namespace
- gm
- Source revision
- legacy-oem-dtc-r2-20260924
Reference family assigned by the production catalog. An entry in this family is not proof of a fault or ECU support on every listed vehicle.
What should I check before using this definition?
Keep the full code, module, status and freeze-frame data. Confirm the vehicle’s make, model, year and current manufacturer service information before choosing a repair. This entry does not identify a failed part by itself.
Organize a scan report or recordingSource and applicabilityOBD Lens production library legacy-owner-2026-10-09-v81. This is a scoped technical reference, not a scan of your car. A catalog relationship does not certify that every ECU, year or engine returns the same signal or code definition.
Read the reference method OBD Lens reference library · catalog legacy-owner-2026-10-09-v81. Sources and scope
OBD Lens