P2188

DTC P2188 SYSTEM TOO RICH AT IDLE (BANK 1)

GENERAL DESCRIPTION
In order to provide the best possible combination of DRIVEABILITY, fuel economy and emission control, the ECM uses a closed loop air/fuel metering system. The ECM monitors the HO2S signal voltage and adjusts fuel delivery based it in closed loop fuel control. Changes in fuel delivery will be indicated by the long-term and the short-term fuel trim values. The ideal fuel trim value is around 0%. The ECM will add fuel when the HO2S signal is indicating a lean condition. Additional fuel is indicated by fuel trim values that are above 0%. The ECM will reduce fuel when the HO2S signal is indicating a rich condition. Reduction in fuel is indicated by fuel trim values that are below 0%. The DTC relevant to fuel trim will be set when the amount reaches excessive levels because of a lean or rich condition.

DTC DESCRIPTION
If the lambda controller reaches the maximum or minimum threshold, then feedback control is no longer possible and emissions will be increased. The ECM sets DTC P2188 if no proportional post catalyst fuel trim adaptation occurs for a defined time after the lambda controller has reached its minimum threshold at idle.

DTC Detecting Condition:

SIGNAL WAVEFORM AND DATA

1. Scan Tool Display for HO2S.

2. Scan Tool Display for MAF.

3. Scan Tool Display for TPS 1 & TPS 2.

MONITOR DTC STATUS

NOTE: If any codes relating to injectors, HO2S, ECT (Engine Coolant Temperature) Sensor, Throttle Position sensor, Injectors or Mass Air Flow Sensor are stored, do ALL REPAIRS associated with those codes before proceeding with this troubleshooting tree.

1. Connect scan tool and select "Diagnostic Trouble Codes (DTCs)" mode.
2. Press F4 (DTAL) to select DTC information from the DTCs menu.
3. Confirm that "DTC Readiness Flag" indicates "Complete". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions.

4. Read "DTC Status" parameter.
5. Is parameter displayed "History (Not Present) fault"?

NOTE:
- History (Not Present) fault : DTC occurred but has been cleared.
- Present fault : DTC is occurring at present time.

YES - Fault is intermittent caused by poor contact in the sensor's and/or the ECM's connector, which was repaired but ECM memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure

NO - Go to next step as below

MONITOR ACTUATION TEST

NOTE: The main purpose of this test is to identify potential engine mechanical condition problems and fuel and ignition systems problems that are not common to all cylinders. For best results, perform this test while maintaining as steady an rpm reading as possible.

Caution: Before beginning tests; set the parking brake, place gear selector in P or N and block drive wheels for safety.

1. Warm up the engine to normal operating temperature and let it idle.
2. Install Scan Tool and select "INJECTOR # 1" parameter on the Actuation Test mode shown in the figure.
3. Monitor engine rpm and shut off the injector #1 by pressing "STRT (F1)" key.
4. Repeat procedure on all injectors and record the engine rpm.

Specification : All cylinders should show an even RPM drop.

5. Was each cylinder's rpm drop within the same value?

YES - Go to next step as below

NO - Cylinders with the least amount of RPM drop are not contributing their share of power. Go to "Fuel System Inspection" procedure.

NOTE: If the RPM loss between cylinders is quite large (200 RPM or more) and engine has high mileage, there is possibility of engine wear. Perform compression test with pressure gauge to check the engine wear.

CHECK INTAKE/EXHAUST SYSTEM FOR LEAKAGE
1. Visually/physically inspect the air leakage in intake/exhaust system for the following areas:
- Air cleaner filter element for excessive dirt or for any foreign objects.
- Throttle body inlet for damage or for any foreign objects.
- Throttle bore and throttle plate for chocking and for any foreign objects.
- Restricted exhaust system.

2. Inspect the leakage in EVAP. system for the following conditions:
- Check the EVAP canister for fuel saturation. If the EVAP canister is full of fuel, visually and physically inspect the EVAP and fuel system.

3. Was a problem found in any of the above areas?

YES - Replace or repair as necessary and go to "Verification of Vehicle Repair" procedure

NO - Go to next step as below

SENSOR INSPECTION

NOTE: Refer to "Signal Waveform & Data" in the "General Information" procedure.

1. Visually/physically inspect the front HO2S for the following conditions:
- Ensure that the HO2S is securely installed.
- Silicon contamination. This contamination will be indicated by a white powdery coating on the portion of the sensor exposed to the exhaust stream and this will result in a but false (high) voltage signal
- Fuel, engine coolant or oil contamination
- Use of improper sealant
- If contamination is evident on the HO2S, Fix the source of the sensor contamination before replacing the sensor to prevent future contamination. Go to "Verification of Vehicle Repair" procedure.

2. Visually/physically inspect the MAFS for the following conditions:
- Contamination or deterioration
- Poor connection or damaged harness

3. Check for an intermittent TPS 1 false signal. TPS 1 signal displayed on a scantool should increase steadily when depressing accelerator pedal after starting.
4. Verify that the ECM ground connections are clean and properly tightened.
5. If test result is NG, repair or replace as necessary and go to "Verification of Vehicle Repair" procedure. If OK, go to next step as below.

NOTE: If the contamination is evident on the HO2S or MAFS. Fix the source of the sensor contamination before replacing the sensor to prevent future contamination.

POSITIVE CRANKCASE VENTILATION SYSTEM INSPECTION
1. Check the engine oil level. The 011 level should be between the min. and max. marking. Fill to the correct oil level
2. Check crankcase ventilation valve for improper installation, damaged O-rings and malfunctioning.
3. Repair or replace as necessary and go to "Verification of Vehicle repair" procedure. If O.K, go to next step.

FUEL SYSTEM INSPECTION
1. Fuel Line Pressure inspection
1. Check the fuel for excessive water, alcohol, or other contaminants. Replace contaminated fuel necessary.
2. Install a fuel pressure gage.
3. Inspect fuel pressure with normal idle status.

Specification : 338 - 348 kPa(3.45 - 3.55 kg/sq.cm)

4. Is fuel pressure within the specified value?

YES - Go to next step as below

NO - Inspect the suspected area. Refer to table as below. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.

2. Fuel Pressure Hold inspection
1. Stop the engine and check for a change in the fuel pressure gauge reading.

Specification : After engine stops, the gauge reading should hold for minimum 5 minutes

2. Is fuel pressure within the specified value?

YES - Visually/physically inspect the engine mechanical problem. Repair as necessary and go to "Verification of Repair Vehicle Repair" procedure

NO - Inspect the leakage or malfunctioning of suspected area. Refer to table as below. Necessary and go to "Verification of Vehicle Repair" procedure.

VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verify that the fault has been corrected.
1. Connect scan tool and select "Diagnostic Trouble Codes (DTCs)" mode.
2. Press F4 (DTAL) and confirm that "DTC Readiness Flag" indicates "Complete". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions.
3. Read "DTC Status" parameter.
4. Is parameter displayed "History (Not Present) fault"?

YES - System performing to specification at this time. Clear the DTC

NO - Go to the applicable troubleshooting procedure.