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I have a 2016 Rallye with 145000 miles. Yesterday the car started stalling at speed. There would be a hiccup and the engine would die and throw a check engine light. If i put it in neutral and try to start it it just keeps turning over. Not until I turn the key to the off position and back on that it will start again. It did this multiple times over the 10 miles left I had to drive it home. Then it sat for the rest of the night. I had to take it to work today (about 4 hours of driving) and the car was fine. No issues at all until I was about a mile from home and the same problem started happening. It died 2 times in that last mile. I got home, let it sit for an hour and drove it to the parts store. About a 15 min. drive, no issues. Read the codes and I have a P0171 code (system too lean). I drove the car home no problems. I am thinking fuel filter or something like that. Any ideas?
 

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I have taken the car on many short drives with no issues. The CEL even went off for a few days, but on my drive today (about 2 hours) the CEL came back but the car never died. Still no idea what is causing this....
 

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A fuel pump problem at 145,000 miles is a definite possibility. A slow O2 sensor is also a realistic possibility with that mileage. If you could get access to a better scanner that can graph the O2 switching and see fuel trims, you should be able to isolate the problem.

28 - DTC-Based Diagnostics / MODULE, Powertrain Control (PCM), 2.0L / Diagnosis and Testing

P0171-FUEL SYSTEM 1/1 LEAN

When Monitored and Set Conditions

When Monitored: This diagnostic runs continuously when the following conditions are met:

•With the engine running in closed loop mode.
•The ambient/battery temperature above -6.7°C (20°F).
•Altitude below 2590.8 m (8500 ft).

Set Conditions:

•The Powertrain Control Module (PCM) multiplies short term compensation by the long term adaptive and a certain percentage is exceeded for 30 seconds. A freeze frame is stored.

Default Actions:

•The MIL light will illuminate.

Possible Causes

RESTRICTED FUEL SUPPLY LINE
FUEL PUMP INLET STRAINER PLUGGED
FUEL PUMP MODULE
O2 SENSOR WIRING OPEN OR SHORTED
O2 SENSOR
MAP SENSOR
ENGINE COOLANT TEMPERATURE SENSOR
ENGINE MECHANICAL
FUEL FILTER/PRESSURE REGULATOR
POWERTRAIN CONTROL MODULE (PCM)
 

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Discussion Starter #6
Now at 200k miles. Same issue happens on hot days. I have replaced both O2 sensors. Took it to the dealer, they told me upstream O2 sensor. Replaced it again. Same problem. Mileage is down to 17mpg avg. I have a hard time thinking this is a fuel pump/filter as it's been this way for over 50k miles. Any other ideas?
 

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The 2.4 MultiAir engine can have oil consumption problems and when the oil level is low, the engine will shut off for no apparent reason. Check the oil level. That said, low oil will not cause a P0171. I have listed possible causes. Checking fuel pump pressure on a Dart is not even listed in the FSM. A fuel pump can have low pressure and still appear to be functioning normally. Are you getting any other codes? The 2.4 upstream O2 sensor has 6 wires! Any sensor signal problem getting info through the wires will not be solved by replacing the sensor if a wire is intermittent.
 

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Discussion Starter #8
No other codes. Is there a way to test the harness to be sure there isn't a short on one of those 6 wires? Below 90 degrees the car runs fine, just low gas mileage. Starting it for the first time each day, it acts like it's going to die, then kicks up the RPMs. I looked for a Schrader valve to test fuel pressure, but was unable to locate one. I sprayed down the engine to test for vacuum leaks. No luck. I guess I need to figure out the various sensor locations and test for those sensors. I also added a ground wire hoping it was a grounding issue. While that seems to have solved other issues, it did not solve this. Any advice on how to proceed?
 

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Here is the complete diagnostic tree. Looks like they buried the fuel pump pressure test here. If you are unsure of any specific sensor location, please post again.

28 - DTC-Based Diagnostics / MODULE, Powertrain Control (PCM), 2.4L / Diagnosis and Testing

P0171-FUEL SYSTEM 1/1 LEAN

124572


Theory of Operation

The wide-band O2 Sensor operates differently than traditional O2 Sensors. The wide-band O2 Sensor tip consists of two cells that provide different functions, a measurement chamber and a detection chamber with pumping capabilities. The oxygen pumping function is the ability to pump oxygen into or out of the measurement chamber depending on the level of oxygen in the measurement chamber. This function provides the wide-band sensing capabilities and is critical for proper oxygen measurement. The O2 Sensor Reference circuit provides a common bias supply to both the O2 Sensor Signal and the O2 Sensor Pump Cell Current circuits.

During normal operation, the O2 Sensor Reference voltage and O2 Sensor Signal voltage will be a fixed voltage value. The O2 Sensor Current Pump voltage will switch from between 0.45 volts above and below the fixed O2 Sensor Return voltage, allowing current to flow in either direction through the pump. This correlates with the pumping of oxygen into and out of the measurement chamber. On a properly operating vehicle, this happens very quickly and the voltage reading should maintain a steady 0.45 volts when taking a voltage measurement between the O2 Sensor Signal circuit and the O2 Sensor Reference circuit of the O2 Sensor with the engine running and the O2 Sensor operating in closed loop.

When the exhaust stream has a lean air/fuel ratio (high oxygen content) the pumping element voltage will move toward +0.45 volts pumping oxygen out of the measurement chamber. When the exhaust stream has a rich air/fuel ratio (relatively low oxygen content) the pumping element voltage will move toward -0.45 volts pumping oxygen into the measurement chamber.


When Monitored and Set Conditions

When Monitored: This diagnostic runs continuously when the following conditions are met:

•With the engine running in closed loop mode.
•The ambient/battery temperature above -6.7°C (20°F).
•Altitude below 2590.8 m (8500 ft).


Set Conditions:

•The Powertrain Control Module (PCM) multiplies short term compensation by the long term adaptive and a certain percentage is exceeded for 30 seconds. A freeze frame is stored.

Default Actions:

•The MIL light will illuminate.


Possible Causes

RESTRICTED FUEL SUPPLY LINE
FUEL PUMP INLET STRAINER PLUGGED
FUEL PUMP MODULE
O2 SENSOR WIRING OPEN OR SHORTED
O2 SENSOR
MAP SENSOR
ENGINE COOLANT TEMPERATURE SENSOR
ENGINE MECHANICAL
FUEL FILTER/PRESSURE REGULATOR
POWERTRAIN CONTROL MODULE (PCM)


Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).


1.ECT SENSOR OPERATION

NOTE: For this test to be valid, the thermostat must be operating correctly.

NOTE: This test works best if performed on a cold engine (cold soak).

1. Turn the ignition on.

2. With the scan tool, read the Engine Coolant Temperature (ECT) Sensor value. If the engine was allowed to sit overnight (cold soak), the temperature value should be a sensible value that is somewhere close to the ambient temperature.

NOTE: If engine coolant temperature is above 82°C (180°F), allow the engine to cool until 65°C (150°F) is reached.

3. Start the Engine.

4. During engine warm-up, monitor the Engine Coolant Temperature (ECT) Sensor value. The temperature value change should be a smooth transition from start up to normal operating temperature 82°C (180°F). The value should reach at least 82°C (180°F).

Did the ECT value increase smoothly and did it reach at least 82°C (180°F)?

Yes

•Go To 2

No

•Verify that there is good pin to terminal contact in the ECT Sensor and Powertrain Control Module connectors. If OK, replace the Engine Coolant Temperature Sensor. (Refer to 07 - Cooling/Engine/SENSOR, Coolant Temperature - Removal) .
•Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).


2.CHECK FOR AN ACTIVE DTC

1. Diagnose all other DTCs before continuing.

2. Start the engine.

3. Allow the engine to reach normal operating temperature.

4. With the scan tool, read DTCs and record on the repair order.

NOTE: It may be necessary to drive the vehicle to meet the conditions to set this DTC, try to repeat the conditions in which the fault originally set by reviewing the Freeze Frame data.

Is the DTC active or pending?

Yes

•Go To 3

No

•Perform the INTERMITTENT CONDITION diagnostic procedure. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).


3.CHECK THE O2 SENSOR 1/1 VOLTAGE READINGS

NOTE: This DTC will set due to poor engine performance as well as a faulty O2 Sensor. If the vehicle exhibits any fuel system or driveability issues, or has any other driveability DTCs present, repair those concerns before proceeding with this test.

1. Start the engine and allow it to idle.

NOTE: If the Powertrain Control Module detects an active open or short on any of the O2 Sensor 1/1 circuits, it will power down all of the O2 Sensor circuits to protect the O2 Sensor PCM internal Application-Specific Integrated Circuit (ASIC) from being damaged.

2. Carefully back-probe the O2 Sensor 1/1 harness connector and measure the voltage at the (K41) O2 Sensor Signal circuit and the (K902) O2 Sensor Return circuit to ground.

NOTE: The (K902) O2 Sensor 1/1 Return circuit voltage should read approximately 3.8 volts and the (K41) O2 Sensor 1/1 Signal circuit should read between approximately 3.35 volts and 4.25 volts if operating normally with no opens or shorts.

Do the circuit voltages read as described?

Yes

•Perform the INTERMITTENT CONDITION diagnostic procedure. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

No

•Go To 4


4.CHECK THE O2 SENSOR 1/1 CIRCUITS FOR A SHORT TO VOLTAGE

1. Turn the ignition off.

2. Disconnect the O2 Sensor 1/1 harness connector.

3. Turn the ignition on.

4. Measure for voltage at the:
•(K41) O2 Sensor 1/1 Signal circuit at the O2 Sensor 1/1 harness connector.

•(K902) O2 Sensor 1/1 Return circuit at the O2 Sensor 1/1 harness connector.

•(K89) O2 Sensor 1/1 Current Pump circuit at the O2 Sensor 1/1 harness connector.

Do any of the circuits measure above 0.5 volts?

Yes

•Repair the circuit that measured above 0.5 volts for a short to voltage.
•Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

No

•Go To 5


5.CHECK THE O2 SENSOR 1/1 CIRCUITS FOR A SHORT TO GROUND

1. Turn the ignition off.

2. Disconnect the PCM C2 harness connector.

3. Check for continuity between ground and the:
•(K41) O2 Sensor 1/1 Signal circuit at the O2 Sensor 1/1 harness connector.

•(K902) O2 Sensor 1/1 Return circuit at the O2 Sensor 1/1 harness connector.

•(K89) O2 Sensor 1/1 Current Pump circuit at the O2 Sensor 1/1 harness connector.

•(K79) O2 Sensor 1/1 Heater Control circuit at the O2 Sensor 1/1 harness connector.

Is there continuity between ground and any of the above circuits?

Yes

•Repair the circuit(s) that shows continuity for a short to ground.
•Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

No

•Go To 6


6.CHECK THE O2 SENSOR 1/1 CIRCUITS FOR AN OPEN OR HIGH RESISTANCE

CAUTION:
Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install the GPEC Diagnostic Adaptor to perform the diagnosis.

1. Connect the Adapter, GPEC Diagnostic 10436 .

2. Measure the resistance of the:
•(K41) O2 Sensor 1/1 Signal circuit between the O2 Sensor 1/1 harness connector and the GPEC Adaptor.

•(K902) O2 Sensor 1/1 Return circuit between the O2 Sensor 1/1 harness connector and the GPEC Adaptor.

•(K89) O2 Sensor 1/1 Current Pump circuit between the O2 Sensor 1/1 harness connector and the GPEC Adaptor.

•(K79) O2 Sensor 1/1 Heater Control circuit between the O2 Sensor 1/1 harness connector and the GPEC Adaptor.

Is the resistance below 3.0 Ohms for each of the above circuits?

Yes

•Go To 7

No

•Repair the circuit that measured above 3.0 Ohms for an open or high resistance.
•Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).


7.CHECKING FUEL PRESSURE

WARNING:
The fuel system is under a constant pressure (even with the engine off). Before testing or servicing any fuel system hose, fitting or line, the fuel system pressure must be released. Failure to follow these instructions can result in possible serious or fatal injury.

1. Turn the ignition off.

2. Install Fuel Pressure Decay Tester 8978A to the fuel rail.

3. Turn the ignition on.

4. With the scan tool, actuate the Fuel System test and observe the fuel pressure gauge.

NOTE: Fuel pressure specification: 400 kPa +/- 14 kPa (58 psi +/- 2 psi).

5. Turn the ignition off.

Choose a conclusion that best matches your fuel pressure reading.

Within Specification

•Go To 8

Above Specification

•Replace the fuel filter/pressure regulator. (Refer to 14 - Fuel System/Fuel Delivery/MODULE, Fuel Pump - Removal) .
•Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

Below Specification

•Go To 13


8.O2 SENSOR 1/1 HEATER OPERATION

1. Turn the ignition off.

2. Reconnect the PCM C2 harness connector and the O2 Sensor 1/1 harness connector.

NOTE: Wait a minimum of 10 minutes to allow the O2 Sensor to cool down before continuing the test. Allow the O2 Sensor voltage to stabilize at 5.0 volts.

3. Turn the ignition on.

4. With the scan tool, actuate the O2 Heater 1/1 Test.

5. With the scan tool, monitor O2 Sensor 1/1 voltage for at least two minutes.

Does the voltage stay above 4.5 volts?

Yes

•Verify that there is good pin to terminal contact in the O2 Sensor 1/1 and Powertrain Control Module connectors. If OK, replace the O2 Sensor. (Refer to 14 - Fuel System/Fuel Injection/SENSOR, Oxygen - Removal) .
•Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

No

•Go To 9


9.MAP SENSOR OPERATION

1. Turn the ignition off.

2. Connect a Vacuum Gauge to a Manifold Vacuum source.

3. Start the engine.

4. Allow the engine to idle.

NOTE: If engine will not idle, maintain a constant rpm above idle.

5. With the scan tool, read the MAP Sensor vacuum value.

Is the scan tool reading within 1" of Hg on the Vacuum Gauge reading?

Yes

•Go To 10

No

•Verify that there is good pin to terminal contact in the MAP Sensor and Powertrain Control Module connectors. If OK, replace the MAP Sensor. (Refer to 14 - Fuel System/Fuel Injection/SENSOR, Manifold Air Pressure (MAP) - Removal).
•Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).


10.ENGINE MECHANICAL PROBLEm

1. Turn the ignition off.

2. Check for any of the following conditions/mechanical problems:
•AIR INDUCTION SYSTEM - must be free from leaks.
•ENGINE VACUUM - must be at least 13 inches in neutral
•ENGINE VALVE TIMING - must be within specifications
•ENGINE COMPRESSION - must be within specifications
•ENGINE EXHAUST SYSTEM - must be free of any restrictions or leaks.
•ENGINE PCV SYSTEM - must flow freely
•TORQUE CONVERTER STALL SPEED - must be within specifications
•POWER BRAKE BOOSTER - no internal vacuum leaks
•FUEL - must be free of contamination
•FUEL INJECTOR - plugged or restricted injector; control wire not connected to correct injector

Are there any engine mechanical problems?

Yes

•Repair as necessary.
•Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

No

•Go To 11


11.1/1 O2 SENSOR

1. Turn the ignition off.

2. Replace the O2 Sensor and reconnect the harness connector.

3. Turn the ignition on.

4. With the scan tool, erase DTCs.

5. Start the engine and allow it to idle long enough for the O2 Sensor to enter closed loop operation.

6. With the scan tool, read DTCs.

Is the DTC active or pending?

Yes

•Go To 12

No

•Repair is complete.
•Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).


12.CHECK RELATED PCM AND COMPONENT CONNECTIONS

1. Perform any Service Bulletins that apply.

2. Disconnect all PCM harness connectors.

3. Disconnect all related in-line harness connections (if equipped).

4. Disconnect the related component harness connectors.

5. Inspect harness connectors, component connectors, and all male and female terminals for the following conditions:
•Proper connector installation.
•Damaged connector locks.
•Corrosion.
•Other signs of water intrusion.
•Weather seal damage (if equipped).
•Bent terminals.
•Overheating due to a poor connection (terminal may be discolored due to excessive current draw).
•Terminals that have been pushed back into the connector cavity.
•Check for spread terminals and verify proper terminal tension.

Repair any conditions that are found.

6. Reconnect all PCM harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.

7. Reconnect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.

8. Reconnect all related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.

9. With the scan tool, erase DTCs.

10. Test drive or operate the vehicle in accordance with the when monitored and set conditions.

11. With the scan tool, read DTCs.

Did the DTC return?

Yes

•Replace the Powertrain Control Module in accordance with the Service information. (Refer to 08 - Electrical/8E - Electronic Control Modules/MODULE, Powertrain Control - Removal) .
•Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

No

•Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
•Test complete.


13.RESTRICTED FUEL SUPPLY LINE

WARNING:
The fuel system is under a constant pressure (even with the engine off). Before testing or servicing any fuel system hose, fitting or line, the fuel system pressure must be released. Failure to follow these instructions can result in possible serious or fatal injury.

1. Turn the ignition off.

2. Raise vehicle on hoist and disconnect the fuel pressure line at the fuel pump module.

3. Install Fuel Pressure Decay Tester 8978A between the fuel supply line and the fuel pump module.

4. Turn the ignition on.

5. With the scan tool, actuate the ASD Fuel System test and observe the fuel pressure gauge.

NOTE: Fuel pressure specification: 400 kPa +/- 14 kPa (58 psi +/- 2 psi).

Is the fuel pressure within specification?

Yes

•Repair or replace fuel supply line as necessary.
•Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

No

•Go To 14


14.FUEL PUMP INLET STRAINER

WARNING:
The fuel system is under a constant pressure (even with the engine off). Before testing or servicing any fuel system hose, fitting or line, the fuel system pressure must be released.

1. Turn the ignition off.

2. Remove the Fuel Pump Module and inspect the Fuel Inlet Strainer.

Is the Fuel Inlet Strainer plugged?

Yes

•Replace the Fuel Pump Inlet Strainer. (Refer to 14 - Fuel System/Fuel Delivery/MODULE, Fuel Pump - Removal) .
•Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

No

•Go To 15


15.FUEL PUMP MODULE

Repair

•Verify that there is good pin to terminal contact in the Fuel Pump Module, Relay and Powertrain Control Module connectors. If OK, replace the Fuel Pump Module. (Refer to 14 - Fuel System/Fuel Delivery/MODULE, Fuel Pump - Removal) .
•Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
 
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