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Home >> Chrysler >> 2007 >> PT Cruiser Base, 2D Convertible, Standard >> Repair and Diagnosis >> Engine Performance >> System >> DTCS P0129 To P0339 >> P0171-Fuel System 1/1 Lean >> Diagnostic Test

Diagnostic Test

  1. 1) ACTIVE DTC 

    Diagnose all other trouble codes before continuing.

    NOTE: Check for contaminants that may have damaged an O2 Sensor: contaminated fuel, unapproved silicone, oil and coolant.

    Ignition on, engine not running.

    With a scan tool, read DTCs.

    Is the DTC active at this time? 

    Yes 

    1. Go to  2).

    No 

    1. Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
    2. Perform POWERTRAIN VERIFICATION TEST .
  2. 2) 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 personal injury or death.

    Install a fuel pressure gauge to the fuel rail.

    Ignition on, engine not running.

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

    NOTE: Fuel pressure specification is 407 kPa +/- 34 kPa (59 psi +/- 5 psi).

    Turn the ignition off.

    CAUTION: Stop All Actuations.

    Choose a conclusion that best matches your fuel pressure reading. 

    Within Specification 

    1. Go to  3).

    Above Specification 

    1. Replace the fuel filter/pressure regulator.
    2. Perform POWERTRAIN VERIFICATION TEST .

    Below Specification 

    1. Go to  12).
  3. 3) O2 SENSOR OPERATION 

    Start the engine.

    Allow the engine to reach normal operating temperature.

    NOTE: If one of the O2 Sensor's Signal or Return circuit is shorted to ground the scan tool will display all O2 Sensor voltage readings low. The O2 Sensor that is shorted to ground will display a voltage reading near or at 0 volts.
    NOTE: If one of the O2 Sensor Signal or Return circuits are shorted to voltage, the scan tool will display all O2 Sensor voltage readings high.
    NOTE: After the repairs have been made, verify proper O2 Sensor operation. If all the O2 Sensor voltage readings have not returned to normal, follow the diagnostic procedure for the remaining O2 Sensors.

    With a scan tool, monitor all of the O2 Sensor voltage readings.

    Is the voltage switching between 2.5 and 3.4 volts for all the O2 Sensors? 

    Yes 

    1. Go to  4).

    No 

    1. Go to  8).
  4. 4) 1/1 O2 SENSOR HEATER OPERATION 

    Turn the ignition off.

    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.

    Ignition on, engine not running.

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

    With the scan tool, monitor 1/1 O2 Sensor voltage for at least 2 minutes.

    Does the voltage stay above 4.5 volts? 

    Yes 

    1. Replace the 1/1 O2 Sensor.
    2. Perform POWERTRAIN VERIFICATION TEST .

    No 

    1. Go to  5).
  5. 5) MAP SENSOR OPERATION 

    Ignition on, engine not running.

    With a scan tool, read the Barometric Pressure.

    NOTE: The Barometric Pressure should be approximately equal to the actual barometric pressure. If necessary, compare the value to the value of a known good vehicle of a similar make and model.

    Turn the ignition off.

    Connect a Vacuum Gauge to a Manifold Vacuum source.

    Start the engine.

    Allow the engine to idle.

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

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

    Is the scan tool reading within 1" of the Vacuum Gauge reading and the barometric pressure comparable to a know good vehicle? 

    Yes 

    1. Go to  6).

    No 

    1. Replace the MAP Sensor.
    2. Perform POWERTRAIN VERIFICATION TEST .
  6. 6) 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)

    Ignition on, engine not running.

    With a 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.

    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 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 

    1. Go to  7).

    No 

    1. Replace the Engine Coolant Temperature Sensor.
    2. Perform POWERTRAIN VERIFICATION TEST .
  7. 7) ENGINE MECHANICAL PROBLEM 

    Turn the ignition off.

    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 

    1. Repair as necessary.
    2. Perform POWERTRAIN VERIFICATION TEST .

    No 

    1. Go to  11).
  8. 8) 1/1 O2 SENSOR 
    Fig 1: Checking O2 1/1 Sensor Connector
    GC0041593Courtesy of CHRYSLER LLC

    Ignition on, engine not running.

    Disconnect the 1/1 O2 Sensor harness connector.

    With a scan tool, monitor the 1/1 O2 Sensor voltage.

    O2 Sensor voltage should read 5.0 volts on the scan tool with the connector disconnected.

    Connect a jumper wire between the (K41) Signal circuit and the (K902) O2 Upstream Return circuit in the O2 Sensor harness connector.

    NOTE: The voltage should drop from 5.0 volts to 2.5 volts with the jumper wire in place.

    Did the O2 Sensor voltage change from 5.0 volts to 2.5 volts with the jumper wire installed? 

    Yes 

    1. Replace the O2 Sensor.
    2. Perform POWERTRAIN VERIFICATION TEST .

    No 

    1. Go to  9).
      NOTE: Remove the jumper wire before continuing.
  9. 9) (K41) O2 SENSOR 1/1 SIGNAL CIRCUIT 

    With a scan tool, monitor the 1/1 O2 Sensor voltage reading with the jumper wire removed.

    NOTE: The scan tool will display all O2 Sensor voltage readings approximately 5.0 volts when only one O2 Sensor's Signal circuit is shorted to voltage.
    NOTE: The scan tool will display one O2 Sensor voltage close to zero and the others will read lower than normal when one O2 Sensor Signal circuit contains excessive resistance.

    Is the voltage above 4.8 volts? 

    Yes 

    1. Go to  10).

    No 

    1. Check the (K41) O2 Sensor 1/1 Signal circuit for a short to ground, open or short to voltage. Inspect the O2 Sensor connector and the PCM harness connector. If OK, replace and program the Powertrain Control Module per Service Information.
    2. Perform POWERTRAIN VERIFICATION TEST .
  10. 10) (K902) O2 UPSTREAM RETURN CIRCUIT 
    Fig 2: Measuring For Voltage On O2 Upstream Return Circuit
    GC0041587Courtesy of CHRYSLER LLC

    Disconnect the 1/1 O2 Sensor harness connector.

    Measure the voltage on the (K902) O2 Upstream Return circuit in the O2 Sensor harness connector.

    Is the voltage at 2.5 volts? 

    Yes 

    1. Go to  11).

    No 

    1. Check the O2 Return circuit for a short to ground, open or short to voltage. Inspect the O2 Sensor connector and the PCM harness connector. If OK, replace and program the Powertrain Control Module per Service Information.
    2. Perform POWERTRAIN VERIFICATION TEST .
  11. 11) PCM 
    NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage or terminal push out. Repair as necessary.

    Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.

    Were there any problems found? 

    Yes 

    1. Repair as necessary.
    2. Perform POWERTRAIN VERIFICATION TEST .

    No 

    1. Replace and program the Powertrain Control Module per Service Information.
    2. Perform POWERTRAIN VERIFICATION TEST .
  12. 12) 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 personal injury or death.

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

    Install special 5/16 fuel line adapter tool #6539 between disconnected fuel line and the fuel pump module.

    Attach a fuel pressure test gauge to the T fitting on tool #6539.

    Ignition on, engine not running.

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

    NOTE: Fuel pressure specification is 407 kPa +/- 34 kPa (59 psi +/- 5 psi).
    CAUTION: Stop All Actuations.

    Is the fuel pressure within specification? 

    Yes 

    1. Repair or replace fuel supply line as necessary.
    2. Perform POWERTRAIN VERIFICATION TEST .

    No 

    1. Go to  13).
  13. 13) FUEL PUMP INLET STRAINER 

    Turn the ignition off.

    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.

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

    Is the Fuel Inlet Strainer plugged? 

    Yes 

    1. Replace the Fuel Pump Inlet Strainer.
    2. Perform POWERTRAIN VERIFICATION TEST .

    No 

    1. Go to  14).
  14. 14) FUEL PUMP MODULE 

    If there are no possible causes remaining, view repair. 

    Repair 

    1. Replace the Fuel Pump Module.
    2. Perform POWERTRAIN VERIFICATION TEST .
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