 
ECM monitors errors through checksum. Every information consists of the combination of 0 and 1, checksum means summing up all values in a row. Thus, errors are recognized comparing checksum value and the memory value at ECM.
ECM detects the signal exchages between micro-processor and sensor/actuator.
| Item | Detecting Condition | Possible Cause | 
| DTC Strategy | 
										•
									 Rationality check (The internal ROM check) | 1. Poor connection 2. ECM | 
| Enable Conditions | 
										•
									 - | |
| Threshold Value | 
										•
									 Check sum fault (ROM) | |
| Diagnostic Time | 
										•
									 - | |
| MIL ON Condition | 
										•
									 Immediately |