Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category |
DTC Descriptor
DTC P2178 : Fuel Trim Rich during Cruising/Acceleration (Bank 1)DTC P2180 : Fuel Trim Rich during Cruising/Acceleration (Bank 2)
DTC P2188 : Fuel Trim Rich during Idling/Deceleration (Bank 1)
DTC P2190 : Fuel Trim Rich during Idling/Deceleration (Bank 2)
Circuit Description
The engine control module (ECM) controls the air/fuel metering system in order to provide the best possible combination of driveability, fuel economy, and emission control. Fuel delivery is controlled differently during Open and Closed Loop. During Open Loop, the ECM determines fuel delivery based on sensor signals without heated oxygen sensor (HO2S) input. During Closed Loop, the HO2S inputs are added and used by the ECM to calculate short and long term fuel trim fuel delivery adjustments. If the HO2S indicate a lean condition, fuel trim values will be above 0 percent. If the O2S indicate a rich condition, fuel trim values will be below 0 percent. Short term fuel trim values change rapidly in response to the HO2S signals. Long term fuel trim makes coarse adjustments in order to maintain an air/fuel ratio of 14.7:1.
Conditions for Running the DTC
P2178
| • | Before the ECM can report DTC P2178 failed, DTCs P0008, P0009, P0010, P0011, P0013, P0014, P0016, P0017, P0018, P0019, P0020, P0021, P0023, P0024, P0101, P0121, P0122, P0123, P0133, P0201, P0202, P0203, P0204, P0205, P0206, P0221, P0222, P0223, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0273, P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0335, P0336, P0338, P0443, P0458, P0459, P0461, P0462, P0463, P2068 P2088, P2089, P2090, P2091, P2092, P2093, P2094, and P2095 must run and pass. |
| • | The engine speed is between 1,200-3,400 RPM. |
| • | The mass air flow (MAF) is between 7-83 grams/second. |
| • | The throttle angle is less than 100 percent. |
| • | The engine load is between 17-55 percent. |
| • | The fuel system is in closed loop. |
| • | The engine is not in decel fuel cut-off (DEFCO). |
| • | The long term fuel trim is active. |
| • | The engine coolant temperature (ECT) is greater than 60°C (140°F). |
| • | The intake air temperature (IAT) is less than 61°C (142°F). |
| • | The evaporative emission (EVAP) canister purge solenoid valve is not enabled. |
| • | The fuel level is greater than 12 percent. |
| • | The amount of air flow into the engine is greater than 7,000 grams. |
| • | DTC P2178 run continuously once the above conditions are met for at least 300 seconds. |
P2188
| • | Before the ECM can report DTC P2188 failed, DTCs P0008, P0009, P0010, P0011, P0013, P0014, P0016, P0017, P0018, P0019, P0020, P0021, P0023, P0024, P0101, P0121, P0122, P0123, P0133, P0201, P0202, P0203, P0204, P0205, P0206, P0221, P0222, P0223, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0273, P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0335, P0336, P0338, P0443, P0458, P0459, P0461, P0462, P0463, P2068 P2088, P2089, P2090, P2091, P2092, P2093, P2094, and P2095 must run and pass. |
| • | The engine speed is between 480-1,001 RPM. |
| • | The engine load is between 7-32 percent. |
| • | The MAF is between 1-8 grams per second. |
| • | The fuel system is in closed loop. |
| • | The engine is not in decel fuel cut-off (DEFCO). |
| • | The long term fuel trim is active. |
| • | The engine coolant temperature (ECT) is greater than 60°C (140°F). |
| • | The intake air temperature (IAT) is less than 61°C (142°F). |
| • | The evaporative emission (EVAP) canister purge solenoid valve is not enabled. |
| • | The fuel level is greater than 12 percent. |
| • | The amount of air flow into the engine is greater than 7,000 grams. |
| • | DTC P2188 run continuously once the above conditions are met. |
Conditions for Setting the DTC
P2178
The Total Fuel Trim Avg. is less than -22 percent. The condition exists for 4 seconds or for a cumulative of 30 seconds.
P2188
The Total Fuel Trim Avg. is less than -40 percent. The LT FT Idle/Decel is less than -6 percent. The condition exists for 4 seconds or for a cumulative of 30 seconds.
Action Taken When the DTC Sets
DTCs P2178 and P2188 are Type B DTCs.
Conditions for Clearing the MIL/DTC
DTCs P2178 and P2188 are Type B DTCs.
Diagnostic Aids
| • | A fuel system delivery condition causes this DTC to set. Thoroughly inspect all items that cause a rich condition. Refer to. |
| • | Review the Freeze Frame/Failure Records with a scan tool. |
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Observe the DTC information with a scan tool. DTC P2178, P2180, P2188, or P2190 should not be set.
- Ignition ON, observe the barometric pressure (BARO) sensor pressure parameter and compare the reading on the scan tool to the barometric pressure table. Refer to Altitude Versus Barometric Pressure.
- Engine at normal operating temperature, observe the Total Fuel Trim Avg. parameter with a scan tool. The Total Fuel Trim Avg. should be between -22 to +23 percent.
- Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
| ⇒ | If there are other DTCs set besides DTC P2178, P2180, P2188, or P2190, refer to Diagnostic Trouble Code (DTC) List - Vehicle to diagnosis the applicable DTC. |
| ⇒ | If the BARO sensor pressure is not within the range specified for your altitude, refer to DTC P2227, P2228, or P2229. |
| ⇒ | If not within the specified range, inspect for the following conditions: |
| • | A mass air flow (MAF) sensor signal that is skewed. If the Short Term FT parameters for both banks changes greater than 20 percent when the MAF sensor is disconnected, refer to DTC P0101. |
| • | A collapsed air intake duct |
| • | A restricted air filter element--Refer to Air Cleaner Element Replacement. |
| • | The MAF sensor for foreign objects. |
| • | Excessive fuel in the crankcase--Change the oil as necessary. |
| • | Fuel contamination--Refer to Alcohol/Contaminants-in-Fuel Diagnosis and. Fuel System Cleaning. |
| • | The engine control module grounds for being clean, tight, and in the correct locations |
| • | Rich injectors--Refer to Fuel Injector Solenoid Coil Test. |
| • | Restricted exhaust system--Refer to Symptoms - Engine Exhaust. |
| • | An engine mechanical condition--Refer to Symptoms - Engine Mechanical. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
