SCP (J1850) Invalid or Missing Data for Primary Id
Your vehicle's main computer isn't receiving proper data signals over the SCP (J1850) communication bus, like a radio station losing its broadcast signal. The ECU can't hear critical information it needs to run the engine properly.
The ECU monitors the SCP bus for valid data packets from other modules (transmission, ABS, instrument cluster). If a required primary ID message doesn't arrive within a specific time window or contains invalid checksums, the fault triggers. The ECU expects continuous heartbeat signals at defined intervals.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| SCP Message Response Time | < 100 ms between valid frames | > 150 ms or no response |
| Data Checksum Validity | Checksum matches expected value | Checksum mismatch or corrupted data |
Code U1067 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, U1067 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.