SCP (J1850) Communication Bus Fault
Your vehicle's communication network between control modules has failed, like a broken phone line preventing different departments from talking to each other. This stops critical systems from sharing information and can prevent the engine from running properly.
The ECM monitors the SCP (J1850) bus for valid communication signals between modules at regular intervals. If no valid messages are received or bus voltage drops below threshold, a communication fault is triggered. The bus requires proper voltage levels and signal integrity to maintain network health.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| SCP Bus Voltage | 4.0-6.0V for dominant/recessive states | Below 2V or no signal detected for >1 second |
| Message Reception Rate | Valid messages every 10-50ms | Missing messages or corrupted data packets |
Code U1262 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, U1262 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.