DTC P2178 [L3 R.H.D.]

id0102a2812400

DTC P2178

Fuel system too rich at off idle

DETECTION CONDITION

• The PCM monitors short term fuel trim (SHRTFT), and long term fuel trim (LONGFT) during closed loop fuel control at off-idle. If the LONGFT or the sum total of these fuel trims exceed the preprogrammed criteria, the PCM determines that the fuel system is too rich at off-idle.
Diagnostic support note
• The MIL illuminates if PCM detects the above malfunctioning condition in two consecutive drive cycles or in one drive if while the DTC for the same malfunction has been stored in the PCM.
• The PENDING CODE is available if PCM detects the above malfunction conditions during first drive cycle.
• FREEZE FRAME DATA is available.
• The DTC is stored in the PCM memory.

POSSIBLE CAUSE

• Misfire
• HO2S deterioration
• HO2S 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

Diagnostic procedure

STEP

INSPECTION

ACTION

1
VERIFY FREEZE FRAME DATA HAS BEEN RECORDED
• Has FREEZE FRAME DATA been recorded?
Yes
Go to the next step.
No
Record the FREEZE FRAME DATA on the repair order, then go to the next step.
2
VERIFY RELATED REPAIR INFORMATION AVAILABILITY
• Verify related service repair information availability.
• Is any related repair information available?
Yes
Perform repair or diagnosis according to the available repair 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.
• any other DTC present?
Yes
If a misfire DTC is present, go to Step 8.
If any other DTC is present, go to the appropriate DTC troubleshooting procedure.
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 the troubleshooting procedures for DTC in FREEZE FRAME DATA.
5
VERIFY CURRENT INPUT SIGNAL STATUS (KEY TO ON/IDLE)
• Access the ECT, MAF, TP, and VSS PIDs using the WDS or equivalent.)
• Is there any signal that greatly exceeds the specification when the ignition switch is at the ON position?
Yes
Inspect the suspected sensor and for excessive resistance in the related wiring harnesses.
Repair or replace if necessary.
Then go to Step 15.
No
Go to the next step.
6
VERIFY CURRENT INPUT SIGNAL STATUS UNDER TROUBLE CONDITION
• Inspect the same PIDs as Step 5 while simulating the FREEZE FRAME DATA condition.
• Is there any signal which causes severe variation?
Yes
Inspect the suspected sensor and related wiring harnesses, and repair or replace if necessary.
Then go to Step 15.
No
Go to the next step.
7
VERIFY CURRENT INPUT SIGNAL STATUS OF HO2S
• Access the O2S11 PID using WDS or equivalent.
• Inspect the PID under the following accelerator pedal condition (in Park).
• Is the PID reading normal?
- Above 0.45 V when the accelerator pedal is suddenly depressed (rich condition).
- Below 0.45 V just after release of the accelerator pedal (lean condition)
Yes
Go to the next step.
No
Visually inspect for any gas leakage between the exhaust manifold and HO2S.
Go to Step 15.
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 15.
9
INSPECT PURGE SOLENOID OPERATION
• Perform "purge control system inspection".
• Does the purge control system function properly?
Yes
Go to the next step.
No
Repair or replace any malfunctioning part according to the inspection result, then go to Step 15.
10
INSPECT PCV VALVE OPERATION
• Inspect PCV valve operation.
• Is the PCV valve normal?
Yes
Go to the next step.
No
Replace the PCV valve, then go to Step 15.
11
INSPECT EGR VALVE OPERATION
• Perform "EGR control system Inspection".
• Does the EGR control system function properly?
Yes
Go to the next step.
No
Repair or replace any malfunctioning part according to inspection result, then go to Step 15.
12
INSPECT VTCS OPERATION
• Perform "variable tumble control system" (VTCS) Operation Inspection.
• Does the VTCS work properly?
Yes
Go to the next step.
No
Repair or replace any malfunctioning part according to inspection result, then go to Step 15.
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 15.
If the fuel line pressure is too low, go to the next step.
14
INSPECT FUEL LINE FROM FUEL PUMP TO FUEL DELIVERY PIPE
• Visually inspect fuel line for any leakage.
• Is any fuel leakage found?
Yes
Replace the fuel line, then go to the next step.
No
Inspect for foreign material or stains inside fuel filter (low-pressure).
If there is foreign materials or stains inside the fuel filter (low-pressure), clean the fuel tank and filter.
Go to the next step.
15
VERIFY TROUBLESHOOTING OF DTC P2178 COMPLETED
• Make sure to reconnect all disconnected connectors.
• Clear the DTC from memory using the WDS or equivalent.
• Perform KOER self test.
• Is the PENDING CODE for this DTC present?
Yes
Replace the PCM, then go to the next step.
No
Go to the next step.
16
VERIFY AFTER REPAIR PROCEDURE
• Perform the "AFTER REPAIR PROCEDURE".
• Are any DTCs present?
Yes
Go to the applicable DTC inspection.
No
Troubleshooting completed.