P2188

DTC P2188: Fuel Trim System Rich At Idle

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%. If the Heated Oxygen Sensors (HO2S) indicate a rich condition, fuel trim values will be below 0%. 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 Setting the DTC
- Engine speed is between 700 rpm and 6,000 rpm.
- Engine coolant temperature is between 70 °C and 115 °C.
- Intake air temperature is between -40 °C and 120 °C.
- Throttle position is between 0% and 95%.
- Engine load is between 25 kPa and 99.7 kPa.
- Mass air flow is between 1.5 g/s and 45 g/s.
- Barometric Pressure is greater than 72 kPa.
- Vehicle speed is less than 140 km/h.
- System voltage is greater than 11 V.
- Vehicle is in Closed Loop condition.
- The average of short term fuel trim is greater than 1.5.
- The average of adaptive index multiplier value is greater than 0.76.

Action Taken When the DTC Sets
- The MIL will illuminate after two consecutive ignition cycles in which the diagnostic runs with the fault active.
- The ECM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers.
- A history DTC is stored.

Conditions for Clearing the MIL/DTC
- The MIL will turn OFF after four consecutive ignition cycles in which the diagnostic runs without a fault within the Freeze Frame conditions that the DTC failed.
- A history DTC will clear after 40 consecutive warm up cycles without a fault.
- The DTC(s) can be cleared using the scan tool.
- Disconnecting the ECM battery feed for more than 10 seconds.

Diagnostic Aids
- A fuel delivery condition causes this DTC to set. Thoroughly inspect all items that cause a lean condition.
- For an intermittent condition, refer to Intermittents Intermittents.

Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
1. This step determines if there is a current condition.
2. A vacuum leak causes DTC P2187 to set. Inspect all areas of the engine for a vacuum leak.
Also inspect the Positive Crankcase Ventilation (PCV) valve for being the correct one for this application. Make sure that the engine oil fill cap is in place and that it is tight. Verify that the engine oil dip stick is fully seated.

Step 1-7:

Troubleshooting