DTC P0172:00 [MZR 1.6]

id0102h3934300

DTC P0172:00

Fuel trim system too rich
DETECTION CONDITION
•  The PCM monitors short term fuel trim (SHRTFT) and long term fuel trim (LONGFT) values when closed loop fuel control. If the LONGFT and the sum total of these fuel trims exceed preprogrammed criteria, the PCM determines that the fuel system is too rich.
Diagnostic support note
•  This is a continuous monitor (fuel system).
•  The check engine light 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 (Mode 2)/Snapshot data is available.
•  DTC is stored in the PCM memory.
POSSIBLE CAUSE
•  Misfire
•  Erratic signal to PCM
―  APP sensor signal malfunction
―  ECT sensor signal malfunction
―  MAF sensor signal malfunction
―  TP sensor signal malfunction
―  VSS signal malfunction
•  A/F sensor heater malfunction
•  A/F sensor malfunction
―  Looseness A/F sensor
―  A/F sensor deterioration
•  MAF sensor malfunction
•  Fuel supply system malfunction or improper fuel line pressure
―  Pressure regulator malfunction
―  Fuel pump unit malfunction
―  Fuel leakage on fuel line from fuel distributor and fuel pump
―  Fuel filter clogged or restricted
―  Fuel return hose clogged
•  Improper operation of purge control system
•  Improper operation of variable tumble shutter valve actuator
•  Improper operation of PCV valve
•  PCM malfunction

Diagnostic procedure

STEP

INSPECTION

ACTION
1
IDENTIFY TRIGGER DTC FOR FREEZE FRAME DATA (MODE 2)
•  Perform the Freeze Frame PID Data Access Procedure.
•  Is the DTC P0172:00 on FREEZE FRAME DATA (Mode 2)?
Yes
Go to the next step.
No
Go to the troubleshooting procedures for DTC on FREEZE FRAME DATA (Mode 2).
(See DTC TABLE [MZR 1.6].)
2
VERIFY FREEZE FRAME DATA (MODE 2)/SNAPSHOT DATA AND DIAGNOSTIC MONITORING TEST RESULTS HAVE BEEN RECORDED
•  Have the FREEZE FRAME DATA (Mode 2)/snapshot data and DIAGNOSTIC MONITORING TEST RESULTS (fuel system related) been recorded?
Yes
Go to the next step.
No
Record the FREEZE FRAME DATA (Mode 2)/snapshot data and DIAGNOSTIC MONITORING TEST RESULTS on repair order, then go to the next step.
3
VERIFY RELATED SERVICE INFORMATION AVAILABILITY
•  Verify related Service Information availability.
•  Is any related Service Information available?
Yes
Perform repair or diagnosis according to the available Service Information.
•  If the vehicle is not repaired, go to the next step.
No
Go to the next step.
4
VERIFY RELATED PENDING CODE AND STORED DTC
•  Switch the ignition off, then ON (engine off).
•  Perform the DTC Reading Procedure and Pending Trouble Code Access Procedure.
•  Are any other DTCs present?
Yes
If misfire DTC is present:
•  Go to Step 10.
If other DTC is present:
•  Go to the applicable DTC inspection.
No
If drive ability concern is present:
•  Go to Step 10.
If drive ability concern is not present:
•  Go to the next step.
5
VERIFY CURRENT INPUT SIGNAL STATUS
•  Connect the M-MDS to the DLC-2.
•  Access the following PIDs using the M-MDS.
―  APP1
―  APP2
―  ECT
―  MAF
―  TP REL
―  VSS
•  Is there any signal that is far out of specification when the ignition is switched to ON and the engine runs?
Yes
Repair or replace the malfunctioning parts according to the inspection results, then go to Step 17.
No
Go to the next step.
6
VERIFY CURRENT INPUT SIGNAL STATUS UNDER FREEZE FRAME DATA (MODE 2) CONDITION
•  Perform the PID/DATA Monitor and Record Procedure and access the same PIDs as in Step 5 under the FREEZE FRAME DATA (Mode 2) condition.
•  Is there any signal which causes drastic changes?
Yes
Repair or replace the malfunctioning parts according to the inspection results, then go to Step 17.
No
Go to the next step.
7
INSPECT A/F SENSOR HEATER
•  Inspect the A/F sensor heater.
•  Is there any malfunction?
Yes
Replace the A/F sensor, then go to Step 17.
(See AIR FUEL RATIO (A/F) SENSOR REMOVAL/INSTALLATION [MZR 1.6].)
No
Go to the next step.
8
INSPECT A/F SENSOR
•  Reconnect the A/F sensor connector.
•  Inspect the A/F sensor.
•  Is there any malfunction?
Yes
Go to the next step.
No
Go to Step 10.
9
INSPECT INSTALLATION OF A/F SENSOR
•  Inspect if the A/F sensor is loosely installed.
•  Is the A/F sensor installed securely?
Yes
Replace the A/F sensor, then go to Step 17.
(See AIR FUEL RATIO (A/F) SENSOR REMOVAL/INSTALLATION [MZR 1.6].)
No
Retighten the A/F sensor, then go to Step 17.
(See AIR FUEL RATIO (A/F) SENSOR REMOVAL/INSTALLATION [MZR 1.6].)
10
VERIFY CURRENT INPUT SIGNAL STATUS OF MAF SENSOR
•  Connect the M-MDS to the DLC-2.
•  Start the engine.
•  Access the MAF PID using the M-MDS.
•  Verify that the MAF PID changes quickly according to engine RPM.
•  Is the MAF PID value normal?
Yes
Go to the next step.
No
Replace the MAF/IAT sensor, then go to Step 17.
(See MASS AIR FLOW (MAF)/INTAKE AIR TEMPERATURE (IAT) SENSOR REMOVAL/INSTALLATION [MZR 1.6].)
11
INSPECT FUEL LINE PRESSURE
•  Switch the ignition off.
Note
•  If engine will not start, inspect fuel line pressure with ignition is switched to ON.
•  Inspect fuel line pressure while engine running.
•  Is there any malfunction?
Yes
If fuel pressure is too high:
•  Replace the fuel pump unit, then go to Step 17.
If fuel pressure is low:
•  Go to the next step.
No
Go to Step 13.
12
INSPECT FUEL LINE
•  Visually inspect the fuel line from fuel pump to fuel distributor.
•  Is there any leakage?
Yes
Repair or replace the malfunctioning parts according to the inspection results, then go to Step 17.
No
Inspect the low-pressure side fuel filter for follows:
•  Foreign materials or stain inside fuel filter.
•  If foreign materials or stain is found inside fuel filter (low-pressure side):
―  Clean of fuel tank and filter.
•  If foreign materials or stain is not found:
―  Replace the fuel pump unit.
Go to Step 17.
13
INSPECT LONG TERM FUEL TRIM
•  Switch the ignition off.
•  Disconnect the evaporative hose (purge solenoid valve side) from intake manifold and plug opening end of hose and intake manifold.
•  Access the LONGFT1 PID using the M-MDS.
•  Does it shift to positive value?
Yes
Go to the next step.
No
Go to Step 15.
14
INSPECT PURGE CONTROL SYSTEM OPERATION
•  Perform the Purge Control System Inspection.
•  Is there any malfunction?
Yes
Repair or replace the malfunctioning parts according to the inspection results, then go to Step 17.
No
Go to the next step.
15
INSPECT VARIABLE TUMBLE CONTROL OPERATION
•  Perform the Variable Tumble Control Operation Inspection.
•  Is there any malfunction?
Yes
Repair or replace the malfunctioning parts according to the inspection results, then go to Step 17.
No
Go to the next step.
16
INSPECT PCV VALVE OPERATION
•  Inspect PCV valve operation.
•  Is there any malfunction?
Yes
Replace the PCV valve and the oil separator as a single unit, then go to the next step.
(See POSITIVE CRANKCASE VENTILATION (PCV) VALVE REMOVAL/INSTALLATION [MZR 1.6].)
No
Go to the next step.
17
VERIFY DTC TROUBLESHOOTING COMPLETED
•  Always reconnect all disconnected connectors.
•  Clear the DTC from the PCM memory using the M-MDS.
•  Perform the Drive Mode 03 (A/F sensor heater, HO2S heater, A/F sensor, HO2S and TWC Repair Verification Drive Mode).
•  Perform the Pending Trouble Code Access Procedure.
•  Is the PENDING CODE for this DTC present?
Yes
Repeat the inspection from Step 1.
•  If the malfunction recurs, replace the PCM.
Go to the next step.
No
Go to the next step.
18
VERIFY AFTER REPAIR PROCEDURE
•  Perform the “AFTER REPAIR PROCEDURE”.
•  Are any DTCs present?
Yes
Go to the applicable DTC inspection.
(See DTC TABLE [MZR 1.6].)
No
DTC troubleshooting completed.