Mechanics

OBD CODE 0172

2000 Dodge Neon

2000 Dodge Neon 6 cyl Front Wheel Drive Manual 110, 00 miles

I had OBD code 0172 appear last year, I have replaced by Oxygen sensors and the check engine light comes on and off. It stays on for sometime then it dissapears for awhile also. We have checked to make sure that the gas cap is tight, what else could be wrong.
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Tkwallace@wans.net
August 19, 2008.




The steps taken to check and correct the issue

best of luck

SELF-DIAGNOSTICS - NEON -2000 Dodge Neon

NOTE: Fuel system operation is monitored when engine is running in closed loop and ambient/battery temperature is more than 20 °F (6.6 °C) with altitude of less than 8000 feet. Powertrain Control Module (PCM) conducts a test to determine if fuel system is running too lean or too rich. If PCM determines fuel system is running too rich for 2 trips, the MIL illuminates and DTC is stored in PCM. The MIL will remain on for more than one trip but will turn off if the conditions which caused the DTC to set are not found on subsequent trips. Possible causes for DTC are: Engine Coolant Temperature (ECT) sensor out of calibration, Manifold Absolute Pressure (MAP) sensor out of calibration, Throttle Position (TP) sensor change not smooth or below .92 volt, engine mechanical problem or improper fuel pressure.

DTC P0172: 1/1 FUEL SYSTEM RICH

1.Turn ignition on with engine off. Using scan tool, check for DTCs. If good trip counter is not displayed and equal to zero, go to next step. If good trip counter is displayed and equal to zero, go to step 13 .

2.Using scan tool, monitor TP sensor voltage. While monitoring TP voltage, slowly open and close throttle. If voltage change is smooth, go to next step. If voltage is not smooth, replace TP sensor. Perform TEST VER-5A .

3.Ensure ignition is on. Using scan tool, read TP sensor voltage with throttle fully closed. If TP sensor voltage is .92 volt or less, go to next step. If TP sensor voltage is more than .92 volt, replace TP sensor. Perform TEST VER-5A .

4.Ensure ignition is on. Using scan tool, read Engine Coolant Temperature (ECT) sensor value to indicate engine coolant temperature. 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. Using scan tool, monitor ECT sensor value while warming engine until engine coolant temperature is more than 180 °F (82 °C). If ECT sensor value increases to at least 180 °F (82 °C), go to next step. If ECT sensor value does not increase to 180 °F (82 °C), replace ECT sensor. ECT sensor is screwed into end of cylinder head, just above the flywheel. Perform TEST VER-5A .

5.Using scan tool, read ECT sensor value to indicate engine coolant temperature. 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 if engine is not previously started. Using scan tool, monitor ECT sensor value while warming engine until engine coolant temperature is more than 180 °F (82 °C). If ECT sensor value increases in a smooth transition, go to next step. If ECT sensor value does not increase in a smooth transition, replace ECT sensor. Perform TEST VER-5A .

6.Turn ignition off. Connect vacuum gauge to engine vacuum source. Start engine and allow engine to idle. If engine will not idle, maintain a constant RPM above idle. Using scan tool, read MAP sensor vacuum. If MAP sensor vacuum is within one in. Hg of engine vacuum on vacuum gauge, go to next step. If MAP sensor vacuum is not within one in. Hg of engine vacuum on vacuum gauge, replace MAP sensor. Perform TEST VER-5A .
NOTE: Ensure engine is at normal operating temperature and running in closed loop for this step.

7.Using scan tool under SYSTEM TESTS, go to PURGE VAPORS TEST. Monitor short term adaptive value and press "3". If short term adaptive value changes when "3" is pressed, go to next

step. If short term adaptive value does not change when "3" is pressed, go to NTC-4: CHECKING EVAPORATIVE EMISSION SYSTEM .

8.Check fuel pressure. See TEST NTC-5: CHECKING FUEL DELIVERY . If fuel pressure is within specification, go to step 12 . If fuel pressure is less than specification, go to next step. If fuel pressure is more than specification, replace fuel filter/pressure regulator assembly. Fuel filter/pressure regulator assembly is mounted on fuel pump module. Using scan tool, stop all actuations.

9.Check the following items for possible causes of a fuel system rich condition.

1. Improper Engine Vacuum (Must Be At Least 13 In. Hg In Neutral)
2.Compression Is Not Within Specification
3.Improper Engine Valve Timing
4. Restricted Exhaust System
5.Restricted PCV
6.Improper Torque Converter Stall Speed
7.Internal Vacuum Leak In Power Brake Booster
8.Contaminated Fuel
9.Restricted Injectors Or Improper Injector Wiring If any of the problems listed exist, repair as necessary. Perform FUEL SYSTEM/MISFIRE MONITOR VERIFICATION . If none of the problems listed exist, go to next step.

10.Raise and support vehicle. Release fuel pressure. See FUEL PRESSURE RELEASE . Disconnect fuel pressure line at fuel pump module. Install 5/16" Fuel Line Adapter (6539) between disconnected fuel line and fuel pump module. Attach fuel pressure gauge to fuel line adapter "T" fitting. Turn ignition on with engine off. Using scan tool, actuate ASD FUEL SYSTEM TEST. If fuel pressure is 44.2-54.2 psi (3.1-3.8 kg/cm2 ), replace fuel filter/pressure regulator assembly. Using scan tool, stop all actuations. If fuels pressure is not 44.2-54.2 psi (3.1-3.8 kg/cm2 ), go to next step. 11.Remove fuel pump module. Inspect fuel inlet strainer for plugging. Replace as necessary. If fuel inlet strainer is not plugged, replace fuel pump module. 12.Check following items for possible causes of a fuel system rich condition.
? Improper Engine Vacuum (Must Be At Least 13 In. Hg With Transaxle In Neutral)
? Compression Is Not Within Specification
? Improper Engine Valve Timing
? Restricted Exhaust System
? Restricted PCV
? Improper Torque Converter Stall Speed
? Internal Vacuum Leak In Power Brake Booster
? Contaminated Fuel
? Restricted Fuel Injectors Or Improper Fuel Injector Wiring If any of the problems listed exist, repair as necessary. Perform FUEL SYSTEM/MISFIRE MONITOR VERIFICATION . If none of the problems listed exist, test is complete. 13.At this time, conditions for fuel system lean do not exist or is an intermittent problem. Using scan tool, read FREEZE FRAME data and SIMILAR CONDITIONS. Attempt to duplicate the conditions when DTC was set. If fuel system lean condition reoccurs, go to next step. If fuel

system lean condition does not reoccur, refer to Technical Service Bulletins (TSBs) for related problems. If no problems exist, test is complete.

http://www.2carpros.com/articles/mitchell1eautorepair-car-repair-manuals

BMRFIXIT
Aug 20, 2008.


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