SCP (J1850) Invalid or Missing Data for Door Locks
Your vehicle's door lock system isn't communicating properly with the main computer over the J1850 network bus. Think of it like a phone that can't receive text messages from one contact—the connection exists but the data isn't getting through.
The ECU monitors incoming SCP (J1850) bus messages from the door lock control module at regular intervals. When expected lock status or command data fails to arrive within the timeout window, or arrives with corrupted checksums, the ECU sets this fault. The bus operates at 41.6 kbaud and requires proper voltage levels and termination.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| SCP Message Response Time | < 100 ms between valid messages | > 100 ms or no message received for 3+ cycles |
| Bus Voltage | 4.5V to 5.5V | < 4.5V or > 5.5V; open/short circuit |
Code U1197 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, U1197 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.