DTC P0171 & DTC P0174: FUEL SYSTEM LEAN Dodge Durango I

Note. DTC P0171 indicates 1/1 fuel system lean and DTC P0174 indicates 2/1 fuel system lean.

Note. Fuel system lean condition is monitored when engine is running in closed loop, ambient/battery temperature sensor reading is more than 20°F (-7°C) and altitude is less than 8000 feet. DTC may be stored in Powertrain Control Module (PCM) if PCM determines fuel system is too lean for 2 trips. Possible causes are: defective Engine Coolant Temperature (ECT) sensor, engine mechanical problem, improper fuel pressure, defective fuel system components, defective Manifold Absolute Pressure (MAP) sensor or defective Throttle Position (TP) sensor.

1. Turn ignition on with engine off. Using scan tool, check for DTCs. If DTC SPECIFIC GOOD TRIP counter is displayed and equal to zero, go to next step. If DTC SPECIFIC GOOD TRIP counter is not displayed and equal to zero, go to step 9.
2. Install vacuum "T" fitting and vacuum gauge at vacuum source on intake manifold. Start engine and allow engine to idle. If engine will not idle, maintain a constant RPM above idle. Note engine vacuum on vacuum gauge. Using scan tool, read MAP sensor vacuum. If MAP sensor vacuum is within one in. Hg of engine vacuum on vacuum gauge, shut engine off. Remove vacuum gauge and go to next step. If MAP sensor vacuum is not within one in. Hg of engine vacuum on vacuum gauge, replace MAP sensor. On 4.7L, MAP sensor is located on front of intake manifold. (Схема №43) On 5.2L and 5.9L, MAP sensor is located on side of throttle body. (Схема №44) On all models, perform «TEST VER-5»(ref-9482-S35719050532000102700000).
3. Turn ignition on with engine off. Using scan tool, read TP sensor voltage with throttle fully closed. If TP sensor voltage is 1.1 volts or less, go to next step. If TP sensor voltage is more than 1.1 volts, check for binding throttle condition. If no binding throttle condition exist, replace TP sensor. Perform «TEST VER-5»(ref-9482-S35719050532000102700000). If binding throttle condition exists, repair or replace components as necessary. Perform «TEST VER-5»(ref-9482-S35719050532000102700000).
4. Ensure ignition is on with engine off. Using scan tool, monitor TP sensor voltage while slowly opening and closing the throttle. If TP sensor voltage changes smoothly, go to next step. If TP sensor voltage does not change smoothly, replace TP sensor. Perform «TEST VER-5»(ref-9482-S35719050532000102700000).
5. Thermostat and cooling system must be operating properly when performing this test procedure. Turn ignition on with engine off. Using scan tool in SENSORS mode, read ENG COOLANT TMP DEG. This is the engine coolant temperature value for ECT sensor. If engine coolant temperature is more than 180°F (82°C), allow engine to cool until engine coolant temperature is 150°F (66°C). Start engine and allow engine to idle. Using scan tool in SENSORS mode, read ENG COOLANT TMP DEG again while warming engine to normal operating temperature. The ENG COOLANT TMP DEG reading on scan tool should increase in a smooth transition as engine coolant temperature increases and temperature should become at least 180°F (82°C). If ENG COOLANT TMP DEG reading on scan tool increases in a smooth transition as engine coolant temperature increases and temperature becomes at least 180°F (82°C), shut engine off. Go to next step. If ENG COOLANT TMP DEG reading on scan tool does not increase in a smooth transition as engine coolant temperature increases or temperature does not become at least 180°F (82°C), shut engine off. Replace ECT sensor. On 4.7L, ECT sensor is located near front of intake manifold and contains Black/Light Blue wire and Tan/Black wire in the connector. (Схема №43) On 5.2L and 5.9L, ECT sensor is located near thermostat housing on intake manifold and contains Black/Light Blue wire and Tan/Black wire in the connector. On all models, perform «TEST VER-5»(ref-9482-S35719050532000102700000).
6. Turn ignition off. Check fuel pressure and fuel pump volume. See «TEST NTC-7: CHECKING FUEL DELIVERY»(ref-9482-S09958255042000102700000). If fuel pressure and fuel pump volume are within specification, go to next step. If fuel pressure or fuel pump volume are not within specification, repair fuel system as necessary.
7. Following additional items should be checked as possible causes for fuel system lean condition: Check engine vacuum. Engine vacuum must be at least 13 in. Hg with transmission in Neutral. Check engine valve timing. Check engine compression. Check exhaust system for restrictions. Ensure PCV system is functioning properly. Check torque converter stall speed. Check power brake booster for internal vacuum leak. Check fuel for contamination. Check air intake system for restrictions. Ensure proper fuel injector driver wiring is installed on correct fuel injector. Ensure fuel injector is not plugged or restricted.
8. If any of the problems listed exist, repair as necessary. Perform «TEST VER-7»(ref-9482-S39715858482000102700000). If none of the problems listed exist, test is complete.
9. At this time, conditions for fuel system lean condition does not exist or is an intermittent problem. Using scan tool, read FREEZE FRAME data and SIMILAR CONDITIONS WINDOW data. Attempt to duplicate the conditions when DTC was set. Also, check for related Technical Service Bulletins (TSBs). If no problems and no related TSBs exist, test is complete.