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 DTC P2178 [L8, LF, L3]

DTC P2178 [L8, LF, L3]

id0102a1812400

DTC P2178

Fuel system too rich at off idle

DETECTION CONDITION

• PCM monitors short term fuel trim (SHRTFT), long term fuel trim (LONGFT) during closed loop fuel control at off-idle. If the LONGFT and the sum total of these fuel trims exceed the preprogrammed criteria, the PCM determines that fuel system is too rich at off-idle.
Diagnostic support note
• This is a continuous monitor. (Fuel system)
• MIL illuminates if PCM detects the above malfunctioning 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 PCM detects the above malfunction conditions during first drive cycle.
• FREEZE FRAME DATA is available.
• DTC is stored in the PCM memory.

POSSIBLE CAUSE

• Misfire
• A/F sensor deterioration
• A/F sensor heater malfunction
• MAF sensor malfunction
• Pressure regulator (built-in fuel injection pump) malfunction
• Fuel pump malfunction
• EGR valve improper operation
• VTCS improper operation
• Purge solenoid valve improper operation
• Purge solenoid valve malfunction (stuck open)
• Purge solenoid hoses improper connection
• PCV valve malfunction
• Variable valve timing control system improper operation (LF, L3)
• PCM malfunction

Diagnostic procedure

STEP

INSPECTION

ACTION

1
VERIFY FREEZE FRAME DATA AND DIAGNOSTIC MONITORING TEST RESULTS HAS BEEN RECORDED
• Has FREEZE FRAME DATA been recorded?
Yes
Go to the next step.
No
Record the FREEZE FRAME on the repair order, then go to the next step.
2
VERIFY RELATED REPAIR 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.
3
VERIFY RELATED PENDING CODE OR STORED DTCS
• Turn the ignition switch off, then to the ON position (Engine off).
• Verify 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 applicable DTC inspection.
No
If driveability concern is present, go to Step 8.
If not, go to the next step.
4
IDENTIFY TRIGGER DTC FOR FREEZE FRAME DATA
• Is DTC P2178 on FREEZE FRAME DATA?
Yes
Go to the next step.
No
Go to troubleshooting procedures for DTC on FREEZE FRAME DATA.
5
VERIFY CURRENT INPUT SIGNAL STATUS (IGNITION SWITCH TO THE ON POSITION/IDLE)
• Access APP1, APP2, ECT, MAF, TP and VSS PIDs using the WDS or equivalent.
• Is there any signal that is far out of specification when the ignition switch is at the ON position and the engine runs?
Yes
Inspect the sensor and excessive resistance in related wiring harnesses.
Repair if necessary.
Then go to Step 16.
No
Go to the next step.
6
VERIFY CURRENT INPUT SIGNAL STATUS UNDER TROUBLE CONDITION
• Inspect the same PIDs as Step 5 while simulating FREEZE FRAME DATA condition.
• Is there any signal which causes drastic changes?
Yes
Inspect the sensor and related wiring harnesses, repair or replace it.
Then go to Step 16.
No
Go to the next step.
7
VERIFY CURRENT INPUT SIGNAL STATUS OF A/F SENSOR
• Access O2S11 for P2178 PID using the WDS or equivalent.
• Check PID under following accelerator pedal condition (in PARK (ATX) or NEUTRAL (MTX)).
• Is PID reading normal?

- - 1.0 -1.0 A when idle.

- More than 0.25 mA just after release of accelerator pedal (lean condition).

Yes
Go to the next step.
No
Visually inspect for any gas leakage between the exhaust manifold and the A/F sensor.
Then go to Step 16.
8
VERIFY CURRENT INPUT SIGNAL STATUS OF MAF SENSOR
• Connect the WDS or equivalent to the DLC-2
• Start the engine.
• Access the MAF PID.
• Verify that the MAF PID changes quickly according to engine speed.
• Is the PID normal?
Yes
Go to the next step.
No
Replace the MAF/IAT sensor, then go to Step 16.
9
INSPECT PURGE SOLENOID OPERATION
• Perform the Purge Control System Inspection.
• Does purge control system work properly?
Yes
Go to the next step.
No
Repair or replace the malfunctioning part according to inspection result, then go to Step 16.
10
INSPECT PCV VALVE OPERATION
• Inspect the PCV valve operation.
• Is the PCV valve normal?
Yes
Go to the next step.
No
Replace the PCV valve, then go to Step 16.
11
INSPECT EGR VALVE OPERATION
• Perform the EGR Control System Inspection.
• Does the EGR control system work properly?
Yes
Go to the next step.
No
Repair or replace the malfunctioning part according to inspection result, then go to Step 16.
12
INSPECT VTCS OPERATION
• Perform the Variable Tumble Control Operation Inspection.
• Does the VTCS work properly?
Yes
Go to Step 15. (LF, L3)/Go to Step 16. (L8)
No
Repair or replace the malfunctioning part according to inspection result, then go to Step 16.
13
INSPECT FUEL LINE PRESSURE
• Turn the ignition switch off.
• Inspect the fuel line pressure.
• Is the fuel line pressure normal?
Yes
Go to the next step.
No
If the fuel pressure is too high, replace the fuel pump unit, then go to Step 16.
If the fuel line pressure is low, go to the next step.
14
INSPECT FUEL LINE FROM FUEL PUMP TO FUEL DELIVERY PIPE
• Visually inspect the fuel line for any leakage.
• Is fuel leakage found?
Yes
Replace suspected fuel line, then go to the next step.
No
Inspect for foreign materials or stain inside fuel filter (low-pressure).
If for foreign materials or stain inside fuel filter (low-pressure), clean off the fuel tank and filter.
Then go to the next step.
15
INSPECT VARIABLE VALVE TIMING CONTROL SYSTEM OPERATION
• Inspect variable valve timing control system operation.
• Does variable valve timing control system work properly?
Yes
Go to the next step.
No
Repair or replace the malfunctioning part according to inspection results, then go to the next step.
16
VERIFY TROUBLESHOOTING OF DTC P2178 COMPLETED
• Make sure to reconnect all disconnected connectors.
• Clear the DTC from the PCM memory using the WDS or equivalent.
• Perform the KOER self-test.
• Is the DTC P2178 present?
Yes
Replace the PCM, then go to the next step.
No
Go to the next step.
17
VERIFY AFTER REPAIR PROCEDURE
• Perform the "AFTER REPAIR PROCEDURE".
• Are any DTCs present?
Yes
Go to the applicable DTC inspection.
No
Troubleshooting completed.