SCP (J1850) Invalid or Missing Data for Vehicle Speed
Your vehicle's computer isn't receiving speed data from the J1850 communication bus, like a radio losing its signal. This disrupts systems that depend on knowing how fast you're going.
The ECM monitors the J1850 SCP bus for valid vehicle speed messages from the instrument cluster or body control module. It expects periodic speed data frames at regular intervals with valid checksums and data ranges. If messages are missing, corrupted, or absent for more than a set duration, the fault triggers.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| J1850 Speed Message Timeout | Valid frames received every 100-200ms | No valid message for >500ms or checksum error |
| Speed Data Value Range | 0–255 km/h (0–158 mph) | Out-of-range or implausible value |
Code U1041 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, U1041 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.