SCP (J1850) Invalid or Missing Data for Primary Id
Your vehicle's network communication system isn't receiving required data from a module on the J1850 bus, similar to a phone call where one person can't hear the other. The ECU is expecting a specific message ID that either never arrives or contains corrupted information.
The ECU monitors the J1850 Serial Communications Protocol bus for periodic messages from other modules using specific Primary IDs. When a required message fails to arrive within the expected time window or arrives with invalid data, the ECU logs this fault. The system uses checksums and message timing validation to ensure data integrity.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Message arrival interval | Within expected time window (typically 10-100ms) | Message missing or delayed beyond threshold |
| Data validity checksum | Checksum matches transmitted data | Checksum mismatch indicates corrupted data |
Code U1093 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, U1093 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.