DTC P0172 [13B-MSP]

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DTC P0172

System too rich
DETECTION CONDITION
•  The PCM monitors the short term fuel trim (SHRTFT) and long term fuel trim (LONGFT) when under closed loop fuel control. If the fuel trim is less than the specification, the PCM determines that the system is too rich.
Diagnostic support note
•  This is a continuous monitor (fuel system).
•  The MIL illuminates if the PCM detects the above malfunction condition in two consecutive drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM.
•  PENDING CODE is available if the PCM detects the above malfunction condition during the first drive cycle.
•  FREEZE FRAME DATA is available.
•  The DTC is stored in the PCM memory.
POSSIBLE CAUSE
•  A/F sensor malfunction
•  Fuel line pressure malfunction
•  Fuel pump unit malfunction
•  Purge solenoid valve malfunction
•  Fuel pump speed control malfunction
•  PCM malfunction

Diagnostic procedure

STEP

INSPECTION

ACTION
1
VERIFY FREEZE FRAME DATA AND DIAGNOSTIC MONITORING TEST RESULTS HAVE BEEN RECORDED
•  Have FREEZE FRAME DATA and DIAGNOSTIC MONITORING TEST RESULTS (fuel system related) been recorded?
Yes
Go to the next step.
No
Record the FREEZE FRAME DATA and DIAGNOSTIC MONITORING TEST RESULTS on the repair order, then go to the next step.
2
VERIFY RELATED SERVICE INFORMATION AVAILBAILITY
•  Verify related Service information availability.
•  Is any related Service information available?
Yes
Perform repair or diagnosis according to th available Service information.
•  If the vehicle is not repaired, go to the next step.
No
Go to the next step.
3
VERIFY RELATED PENDING CODE OR STORED DTC
•  Turn the ignition switch off, then to the ON position (engine off).
•  Verify the related PENDING CODE or stored DTCs.
•  Are other DTCs present?
Yes
•  If misfire DTC is present, go to Step 8.
•  If other DTC is present, go to the appropriate DTC inspection.
No
•  If drive ability concern is present, go to Step 8.
•  If other, go to the next step.
4
IDENTIFY TRIGGER DTC FOR FREEZE FRAME DATA
•  Is DTC P0172 on FREEZE FRAME DATA?
Yes
Go to the next step.
No
Go to the FREEZE FRAME DATA DTC inspection.
(See DTC TABLE [13B-MSP].)
5
VERIFY CURRENT INPUT SIGNAL STATUS
•  Connect the M-MDS to the DLC-2.
•  Verify the following PIDs.
―  APP
―  ECT
―  MAF
―  TP REL
―  VSS
•  Are the PIDs normal?
Yes
Go to the next step.
No
Inspect the malfunctioning part according to the inspection results, then go to Step 11.
6
VERIFY CURRENT INPUT SIGNAL STATUS UNDER FREEZE FRAME DATA CONDITION
•  Connect the M-MDS to the DLC-2.
•  Verify the following PIDs under the FREEZE FRAME DATA condition.
―  APP
―  ECT
―  MAF
―  TP REL
―  VSS
•  Are the PIDs normal?
Yes
Go to the next step.
No
Inspect the malfunctioning part according to the inspection results, then go to Step 11.
7
INSPECT A/F SENSOR
•  Inspect the A/F sensor.
•  Is there any malfunction?
Yes
Inspect for following:
•  Air suction at following due to cracks, damages and loosing parts:
―  From air cleaner to throttle body
―  From throttle body to dynamic chamber
―  From dynamic chamber and intake manifold
―  Vacuum hoses
Note
•  Engine speed may change when rust penetrating agent is sprayed on the air suction area.
•  Exhaust gas leakage between exhaust manifold and A/F sensor.
•  Loose installation of A/F sensor.
If there is no malfunction detected, replace the A/F sensor.
(See AIR FUEL RATIO (A/F) SENSOR REMOVAL/INSTALLATION [13B-MSP].)
If there are malfunctions detected, repair or replace the malfunctioning part, then go to Step 11.
No
Go to the next step.
8
INSPECT FUEL LINE PRESSURE
•  Perform the ”FUEL LINE PRESSURE INSPECTION”.
•  Is there any malfunction?
Yes
Replace the fuel pump unit, then go to Step 11.
(See FUEL PUMP UNIT REMOVAL/INSTALLATION [13B-MSP].)
No
Go to the next step.
9
INSPECT LONG TERM FUEL TRIM
•  Connect the M-MDS to the DLC-2.
•  Access the LONGFT1 PID.
•  Compare the LONGFT1 PID with recorded FREEZE FRAME DATA at Step 1.
•  Is the LONGFT1 PID above FREEZE FRAME DATA?
Yes
Inspect the purge solenoid valve.
(See PURGE SOLENOID VALVE INSPECTION [13B-MSP].)
•  If there is any malfunction, replace the purge solenoid valve, then go to Step 11.
No
Go to the next step.
10
INSPECT FUEL PUMP SPEED CONTROL OPERATION
•  Perform the “Fuel Pump Speed Control Operation Inspection”.
•  Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results, then go to the next step.
No
Go to the next step.
11
VERIFY TROUBLESHOOTING OF DTC P0172 COMPLETED
•  Make sure to reconnect all disconnected connectors.
•  Clear the DTC from the PCM memory using the M-MDS.
•  After warming up the engine, maintain the idle status for 1 min or more.
•  Is the PENDING CODE same as the DTC present?
Yes
Replace the PCM, then go to the next step.
(See PCM REMOVAL/INSTALLATION [13B-MSP].)
No
Go to the next step.
12
VERIFY AFTER REPAIR PROCEDURE
•  Perform the “AFTER REPAIR PROCEDURE”.
•  Are any DTCs present?
Yes
Go to the applicable DTC inspection.
(See DTC TABLE [13B-MSP].)
No
DTC troubleshooting completed.