Checking the fuel trime value under detecting condition, if its average exceeds the limit over certain period, ECM/PCM sets P0171. MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.
Item | Detecting Condition | Possible Cause |
DTC Strategy |
•
Monitoring the deviation of short term fuel trim | 1. Air leakage 2. Improper fuel pressure 3. PCV valve stuck 4. Clogging of injector |
Enable Conditions |
•
Engine Coolant Temperature(ECT) > 73°C
•
Lambda control active : No relevant failure(Upstream O2 sensor, Injector valve, ETC in limp home state), Measured Tip temperature > 630°C, Engine coolant temperature > 5.25°C | |
Threshold Value |
•
Short term trim >= 50% | |
Diagnostic Time |
•
90 sec. | |
Mil On Condition |
•
2 driving cycles. |
