Вот описание:
DTC P0172 OR P0175: FUEL TRIM SYSTEM - RICH
Circuit Description
The Engine Control Module (ECM) controls the air/fuel metering system in order to provide the best possible
combination of driveability, fuel economy and emission control. Fuel delivery is controlled differently during
Open and Closed Loop. During Open Loop the ECM determines fuel delivery based on sensor signals, without
oxygen sensor input. During Closed Loop, the oxygen sensor inputs are added and used by the ECM to
calculate fuel trim. If the oxygen sensors indicate a lean condition, fuel trim values will be greater than zero
percent. If the oxygen sensors indicate a rich condition, fuel trim values will be less than zero percent. Short
term Fuel Trim (FT) values change rapidly in response to the Heated Oxygen Sensor (HO2S) voltage signals.
Long term FT values change slower in response to trends in short term FT adjustments. The fuel trim diagnostic
will conduct a test to determine if a rich failure actually exists or if excessive vapor from the EVAP canister is
causing a rich condition. If the ECM detects excessive vapor, then a pass is logged. This DTC is continuously
monitored during operation. If the ECM detects an excessively rich condition, DTC P0172 or P0175 sets.
Conditions For Running DTC
NOTE: After repairs, reset the Long Term fuel with the scan tool Fuel Trim Reset
function.
NOTE: To locate components, see COMPONENT LOCATIONS . For circuit reference,
see WIRING DIAGRAMS . For connector terminal identification, see
CONNECTOR IDENTIFICATION .
? DTC P0030, P0031, P0032, P0050, P0051, P0052, P0101, P0102, P0112, P0113, P0117, P0118, P0121,
P0122, P0123, P0125, P0128, P0103, P0130, P0131, P0132, P0133, P0134, P0135, P0150, P0151,
P0152, P0153, P0155, P0201-P0206, P0221,P0222, P0223, P0261, P0262, P0264, P0265, P0267, P0268,
P0270, P0271, P0273, P0274, P0276, or P0277 not set.
? System is in closed-loop status.
? Fuel level is more than 9.8 percent.
Conditions For Setting DTC
? The LT FT Cruise/Accel parameter is less than -23 percent.
? The LT FT Idle/Decel parameter is less than -8.1 percent.
Actions Taken When DTC Sets
? The control module illuminates the Malfunction Indicator Light (MIL) on the second consecutive ignition
cycle that the diagnostic runs and fails.
? The control module records the operating conditions at the time the diagnostic fails. The first time the
diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic
reports a failure on the second consecutive ignition cycle, the control module records the operating
conditions at the time of the failure. The control module writes the operating conditions to the Freeze
Frame and updates the Failure Records.
Conditions For Clearing MIL/DTC
? Control module turns OFF the Malfunction Indicator Light (MIL) after 3 consecutive ignition cycles that
the diagnostic runs and does not fail.
? A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
? A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other
emission related diagnostic.
? Clear the MIL and DTC with a scan tool.
Diagnostic Procedures
1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, go to
DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS .
2.
Install a scan tool. Start engine. Operate vehicle within the Conditions for Running the DTC. See
CONDITIONS FOR RUNNING DTC . Record the LT FT Cruise/Accel and LT FT Idle/Decel
parameter values. Turn engine off. Turn ignition on, with engine off. Review the Freeze Frame/Failure
Records and record the displayed data for this DTC. Does the scan tool indicate that the LT FT
Cruise/Accel parameter is less than -23 percent? If yes, go to step 4 . If no, go to next step.
NOTE: If any DTCs are set other than DTC P0172 or P0175, diagnose affected DTC
(s) before continuing this test. See DIAGNOSTIC TROUBLE CODE
DEFINITIONS .
3. Does the scan tool indicate that the LT FT Idle/Decel parameter is less than -8.1 percent? If yes, go to
next step. If no, go to DIAGNOSTIC AIDS .
4. Operate engine at idle. Observe the HO2S parameters with a scan tool. Does the scan tool indicate that
the values are within 200-800 mV and fluctuating? If yes, go to next step. If no, go to step 6 .
5. Turn engine off. Visually and physically inspect the inlet screen of the MAF sensor for blockage, vacuum
hoses for splits, kinks, and proper connections, air intake duct for being collapsed or restricted, air filter
for being dirty or restricted, or objects blocking the throttle body. Did you find and correct the condition?
If yes, go to step 8 . If no, go to step 7 .
6. Turn engine off. Inspect the HO2S for proper installation. Verify that the electrical connectors and wires
are secured and are not contacting the exhaust system. Did you find and correct the condition? If yes, go
to step 8 . If no, diagnose fuel system. Refer to FUEL SYSTEM DIAGNOSIS under FUEL SYSTEMS
in BASIC DIAGNOSTIC PROCEDURES - 2.2L & 3.0L VUE article.
7. Inspect for excessive fuel in the crankcase, EVAP control system, and fuel pressure regulator for proper
operation. Did you find and correct the condition? If yes, go to next step. If no, diagnose for an engine
mechanical problem.
8.
Clear the DTCs with a scan tool. Turn ignition off for 30 seconds. Start engine. Operate vehicle within
the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC . You may also
operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did
the DTC fail this ignition? If yes, go to step 2 . If no, go to next step.
9. Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? If yes,
diagnose affected DTC(s). See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are
displayed, system is okay.
Diagnostic Aids
? A skewed MAF sensor may set this DTC. Refer to DTC P0101: MASS AIRFLOW SYSTEM
PERFORMANCE .
? Fuel contamination, such as water and alcohol, will effect fuel trim.
? A skewed ECT sensor may set this DTC.
? An EVAP purge solenoid that is stuck open may set this DTC.
? Review the Failure Records with a scan tool. If an intermittent condition is suspected , refer to
INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 2.2L & 3.0L VUE article.
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