SCP (J1850) Invalid or Missing Data for Experimental #1
The vehicle's communication network isn't receiving expected data from an experimental control module on the J1850 bus. Think of it like a radio station not broadcasting on the right frequency—other devices can't hear the signal.
The ECU monitors the J1850 SCP (Standard Corporate Protocol) bus for valid data frames from experimental control modules. When expected messages don't arrive within the defined timeout window or contain invalid checksums, the ECU logs this fault. The bus operates at 41.6 kbaud and requires proper voltage levels and message timing.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| SCP Bus Message Timeout | Message received within 100-200ms intervals | No valid message received or timeout exceeded |
| Data Validity/Checksum | Valid CRC and proper data format | Corrupted or invalid checksum detected |
Code U1031 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, U1031 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.