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Home >> Dodge and Ram >> 2003 >> Durango Base, 5.9 Z, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 17 (Engine Controls - Self-Diagnostics - 3.9L & 5.9L) >> Diagnostic Tests >> DTC P0172: 1/1 Fuel System Rich Or DTC P0175: 2/1 Fuel System Rich >> Testing

DTC P0172: 1/1 Fuel System Rich Or DTC P0175: 2/1 Fuel System Rich: Testing

WARNING: This page is about a different car, the 2003 Dodge Dakota. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Check for contaminants that may have damaged the O2 sensor, such as contaminated fuel, unapproved silicone, oil or coolant.
NOTE: Any ECT, EVAP, MAP, TP or O2 sensor DTCs must be repaired before continuing.
  1. Turn ignition on, with engine off. With the DRBIII(R) scan tool, read the DTCs and record the related freeze frame data. Is the Good Trip Counter displayed and equal to zero? If yes, go to next step. If no, see INTERMITTENT CONDITION  under SELF-DIAGNOSTIC SYSTEM.
    2. 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. See FUEL SYSTEM PRESSURE RELEASE  .
  2. Release fuel pressure. See FUEL SYSTEM PRESSURE RELEASE  . Install a fuel pressure gauge to fuel pressure test port. Turn ignition on, with engine off. With the DRBIII(R) scan tool, actuate the Automatic Shutdown (ASD) Fuel System test and observe the fuel pressure gauge. Fuel pressure specification is 44.2-54.2 psi (305-373 kPa). Turn the ignition off. Stop all actuations. If fuel pressure is within specification, go to next step. If fuel pressure is more than specification, replace the fuel filter/pressure regulator.
  3. Turn ignition on, with engine off. With the DRBIII(R) scan tool, read the O2 sensor voltage. Is the O2 sensor voltage more than 4.5 volts? If yes, go to next step. If no, go to step  11 .
  4. 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 at 4-5 volts. Turn ignition on, with engine off. With the DRBIII(R) scan tool, actuate the O2 heater test. With the DRBIII(R) scan tool, monitor the O2 sensor voltage for at least 2 minutes. Does the voltage stay at more than 4.5 volts? If yes, replace the O2 sensor. If no, go to next step.
    5. WARNING: When the engine is operating, DO NOT stand in a direct line with the fan. DO NOT put your hands near the pulleys, belts or fan. DO NOT wear loose clothing.
    NOTE: The engine must be at operating temperature and in closed loop to perform this test.
  5. Start the engine. Allow the engine to reach normal operating temperature. With the DRBIII(R) scan tool, select System Tests and perform the Purge Vapors Test. Observe the Short Term Adaptive value and press "3" to flow. Did the Short Term Adaptive value change? If yes, go to next step. If no, diagnose EVAP system by symptom. See DIAGNOSTIC TROUBLE CODE DEFINITIONS  and appropriate TROUBLE SHOOTING - NO CODES article.
    6. NOTE: The throttle must be against the stop in this step.
  6. Turn ignition on, with engine off. With the DRBIII(R) scan tool, read TP sensor voltage. 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.
  7. 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 decrease smoothly? If yes, go to next step. If no, replace the TP sensor.
    8. NOTE: If engine will not idle, maintain a constant RPM more than idle.
  8. Turn the ignition off. Connect a vacuum gauge to a manifold vacuum source. Start the engine and allow it to 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. Remove vacuum gauge before the continuing.
    9. NOTE: For this test to be valid, thermostat must be operating properly. This test works best if performed on a cold soak engine. If engine coolant temperature is more than 180°F (82°C), allow the engine to cool until 150°F (65°C) is reached.
  9. Turn ignition on, with engine off. With the DRBIII(R) scan tool in Sensors, read the Eng Coolant Tmp Deg 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 surrounding temperature (ambient temperature). Start the engine. During engine warm-up, monitor the Eng Coolant Tmp Deg value. The value change should be a smooth transition from start-up to normal operating temperature. The value should reach at least 180°F (82°C). Was the Eng Coolant Tmp Deg 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.
  10. Check for any of the following conditions/mechanical problems:
    • Air induction system must be free from leaks.
    • Engine vacuum must be at least 13 in. Hg with transmission in Neutral.
    • Engine valve timing must be within specifications.
    • Engine compression must be within specifications.
    • 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 must not have any internal vacuum leaks.
    • Fuel must be free of contamination.
    • Fuel injectors must be free of restrictions.
    • Injector control wires must be connected properly, and to the correct injector.

    Are there any engine mechanical problems? If yes, repair as necessary. If no, see INTERMITTENT CONDITION  under SELF-DIAGNOSTIC SYSTEM.

  11. Turn the ignition off. Disconnect the O2 sensor harness connector. Turn ignition on, with engine off. With the DRBIII(R) scan tool, monitor the O2 sensor voltage. Is the O2 sensor voltage more than 4.5 volts? If yes, replace the O2 sensor. If no, go to next step.
  12. Turn the ignition off. Disconnect the PCM harness connectors. Measure the resistance of the O2 sensor signal circuit between the O2 sensor harness connector and the PCM harness connector. Is the resistance less than 5.0 ohms? If yes, go to next step. If no, repair the open in the O2 sensor signal circuit.
  13. Turn ignition on, with engine off. Leave the O2 sensor and PCM harness connectors disconnected. Measure the voltage on the O2 sensor signal circuit at the O2 sensor harness connector. Is the voltage more than 5.2 volts? If yes, repair the short to voltage in the O2 sensor signal circuit. If no, go to next step. Turn ignition off before continuing.
    14. NOTE: Before continuing, disconnect the PCM harness connectors and check the related wiring terminals for corrosion, damage or terminal push out. Repair as necessary.
  14. Using the wiring diagram as a guide, inspect the wire harness and connectors. Visually inspect the related wire harness. Look for any chafed, pierced, pinched, or partially broken wires. Visually inspect both the component and the PCM connectors. Pay particular attention to all power and ground circuits. If there are no possible causes remaining, replace and program the PCM. See PROGRAMMING  .
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