SCP (J1850) Invalid or Missing Data for Chassis Status Request
Your vehicle's computer can't receive required chassis status information over the communication network, like a radio losing its signal. This prevents proper coordination between modules that need to share real-time vehicle data.
The ECM monitors incoming J1850 SCP bus messages containing chassis status data from other modules (ABS, transmission, steering). When expected messages fail to arrive within the specified timeframe or contain invalid data, the ECM triggers this fault. Communication timeout or CRC checksum errors indicate a network failure.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Message Response Time | < 100 milliseconds | > 200 milliseconds or no response |
| Data Validity Check | Valid CRC and checksum | Failed checksum or corrupted data |
Code U1104 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, U1104 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.