Mechanics

CODE

2003 Chrysler Town and Country

Computer problem
2003 Chrysler Town and Country 6 cyl All Wheel Drive Automatic 147890 miles

how do I fix code p0171
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Lincolnn1
February 15, 2010.




DTC P0171: 1/1 FUEL SYSTEM LEAN
NOTE: For component location, see COMPONENT LOCATIONS. For connector identification, see CONNECTOR IDENTIFICATION. For circuit identification and wiring diagram, see WIRING DIAGRAMS. In testing procedures Alpha/Numeric character in parenthesis i.E. (K4) designates circuit. After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Monitored & Set Conditions
System is monitored with engine running in closed loop mode, ambient/battery temperature above 20 F (-7 C) and altitude less than 8000 feet. DTC will set if the Powertrain Control Module (PCM) multiplies short term compensation by long term adaptive and a certain percentage is exceeded for two trips, a freeze frame is stored, the MIL illuminates and a DTC is stored.
Possible Causes
Fuel Pressure Out Of Specs
Good Trip Equal To Zero
Restricted Fuel Supply Line
Fuel Pump Inlet Strainer Plugged
Fuel Pump Module
O2 Sensor
O2 Sensor Signal Circuit Shorted To Ground
O2 Sensor Heater Operation
Throttle Position Sensor Voltage Greater Than 0.92 Volt With Throttle Closed
Throttle Position Sensor Sweep
MAP Sensor Operation
ECT Sensor Operation
Engine Mechanical Problem
Fuel Filter/Pressure Regulator
PCM
Testing
NOTE: Before continuing check for contaminants that may have damaged HO2S such as contaminated fuel, unapproved silicone, oil and coolant.

Turn the ignition on. With the DRBIII(R) scan tool, read DTCs. Is the Good Trip counter displayed and equal to zero? If yes, go to next step. If no, refer to the INTERMITTENT CONDITION under SELF-DIAGNOSTICS SYSTEM.
WARNING: Fuel system is under constant pressure even when ignition is off. Before testing or servicing any fuel system hose, fitting or line, the fuel system pressure must be released.

Release fuel pressure. See FUEL SYSTEM PRESSURE RELEASE. Connect fuel pressure gauge to fuel rail. Turn ignition on. With the DRBIII(R) scan tool, actuate ASD Fuel System test and observe fuel pressure gauge. Fuel pressure should be 53-63 psi (365-434 kPa). Turn ignition off. If fuel pressure is within specification, stop all actuations and go to next step. If fuel pressure is less than specification, stop all actuations and go to step 13. If fuel pressure is greater than specification, stop all actuations. Replace fuel filter/pressure regulator. See FUEL SYSTEMS in REMOVAL & INSTALLATION - CARAVAN, TOWN & COUNTRY, & VOYAGER article.
Turn the ignition on. With the DRBIII(R) scan tool, read the O2 sensor voltage. Is the voltage between 0.4 and 0.6 volt? If yes, go to next step. If no, go to step 10.
Turn the ignition off. 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 between 0.4 and 0.6 volt. Turn the ignition on. With the DRBIII(R) scan tool, actuate the O2 Heater Test. With the DRBIII(R) scan tool, monitor O2 sensor voltage for at least 2 minutes. Does the voltage stay between 0.4 and 0.6 volt? If yes, replace the O2 sensor. If no, go to next step.
Turn the ignition on. With the DRBIII(R) scan tool, read TP sensor voltage. The throttle must be against the stop. Is the voltage 0.92 volt or less with the throttle closed? If yes, go to next step. If no, check for a binding throttle condition. If okay, replace the TP sensor.
Turn the ignition on. With the DRBIII(R) scan tool, read the TP sensor voltage. While monitoring the DRBIII(R) scan tool, slowly open and close the throttle. Does the voltage increase and decease smoothly? If yes, go to next step. If no, replace the TP sensor.
Turn the ignition off. Connect a vacuum gauge to a manifold vacuum source. Start the engine. Allow the engine to idle. If engine will not idle, maintain a constant RPM above idle. With the DRBIII(R) scan tool in Sensors, read the MAP sensor vacuum value. Is the DRBIII(R) scan tool reading within 1 in. Hg of the vacuum gauge reading? If yes, go to next step. If no, replace the MAP sensor.
For this test to be valid, the thermostat must be operating correctly. This test works best if performed on a cold engine (cold soak). Turn the ignition on. With the DRBIII(R) 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. If engine coolant temperature is above 180 F (82 C), allow the engine to cool until 150 F (65 C) is reached. Start the engine. During engine warm-up, monitor the ECT sensor value. The temperature value change should be a smooth transition from start up to normal operating temperature 180 F (82 C). The value should reach at least 180 F (82 C). Did the engine coolant temperature value increase a smooth transition and did it reach at least 180 F (82 C)? If yes, go to next step. If no, replace the ECT sensor.
Check for any of the following conditions/mechanical problems.
Ensure air intake system is free from leaks.
Ensure engine vacuum is at least 13 in. Hg at idle in Park or Neutral.
Ensure valve timing is correct.
Ensure engine compression is within specification.
Ensure exhaust system is free from restrictions or leaks.
Ensure PCV system flows freely.
Ensure torque converter stall speed is within specification.
Ensure power brake booster has no internal vacuum leaks.
Ensure fuel is not contaminated.
Ensure fuel injectors are not restricted.
Ensure fuel injector harness connectors are connected to correct fuel injectors.
Are there any engine mechanical problems? If yes, repair as necessary. If no, test is complete.
Turn the ignition on. Disconnect the O2 sensor harness connector. With the DRBIII(R) scan tool, monitor the O2 sensor voltage. Is the O2 sensor voltage between 0.4 and 0.6 volt? If yes, replace the O2 sensor. If no, go to next step.
Turn the ignition off. Disconnect the O2 sensor harness connector. Disconnect the PCM harness connector. Measure the resistance of the O2 sensor signal circuit in the PCM harness connector to ground. Is the resistance below 5.0 ohms? If yes, repair the O2 sensor signal for a short to ground. If no, go to next step.
NOTE: Before continuing disconnect the PCM harness connector and check the related wiring terminals for corrosion, damage or terminal push out. Repair as necessary.

Using the wiring diagram as a guide, inspect the wire harness and connectors. Pay particular attention to all power and ground circuits. If there are no possible causes remaining, replace and program the PCM. See PROGRAMMING.
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.

Turn the ignition off. Release fuel pressure. See FUEL SYSTEM PRESSURE RELEASE. Raise vehicle on hoist, and disconnect the fuel pressure line at the fuel pump module. Install special 5/16 Fuel Line Adapter (6539) between disconnected fuel line and the fuel pump module. Attach a fuel pressure test gauge to the " T" fitting on fuel line adapter. Turn the ignition on. With the DRBIII(R) scan tool, actuate the ASD Fuel System test and observe the fuel pressure gauge. Note fuel pressure reading, stop ASD Fuel System test and turn ignition off. If fuel pressure is 53-63 psi (365-434 kPa), repair or replace fuel supply line as necessary. If fuel pressure is not 53-63 psi (365-434 kPa), go to next step.
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.

Release fuel pressure. See FUEL SYSTEM PRESSURE RELEASE. Remove fuel pump module from fuel tank. Inspect fuel inlet strainer. Is the fuel inlet strainer plugged? If yes, replace fuel inlet strainer. If no, go to next step.
There are no possible causes remaining, replace the fuel pump module.

BMRFIXIT
Feb 15, 2010.


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