Lost Communication With Emissions Critical Control Information
Your engine computer lost its connection to a critical emissions control module, like a phone losing signal from its tower. The vehicle can't properly communicate with emission system components, which may trigger limp mode or prevent the engine from starting.
The ECM continuously monitors CAN bus communication with emissions critical modules (SCR, DPF, or EGR controllers). It expects periodic heartbeat messages and valid data packets within specific timeframes. Loss of these signals for a defined duration triggers the fault.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| CAN Bus Message Timeout | Message received every 10-100ms | No message received for >500ms |
| Data Validity Check | CRC and checksum valid | Corrupted or missing CRC checksum |
Code U0113 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, U0113 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.