Note: Do not clear the DTCs or reset the keep alive memory (KAM).
Note: Fuel trim values at idle are more sensitive to a vacuum leak. The vacuum leak (unmetered air) represents a larger portion of the total air flow at idle than at part throttle.
Note: The barometric pressure (BARO) PID is not a recommended PID to monitor when diagnosing a vacuum leak. Barometric pressure is calculated during high engine load, when the vacuum leak represents a small portion of the total air flow.
Note: When calculating the total fuel correction in the following steps, if LONGFT1 equals +13% and SHRTFT1 equals +23%, the total fuel correction for bank 1 equals +36%. If LONGFT2 equals +24% and SHRTFT2 equals -3% the total fuel correction for bank 2 equals +21%.
Note: If the freeze frame ECT PID is available, stabilize the engine at the temperature recorded by the freeze frame ECT PID. If the freeze frame ECT PID is not available, maintain the engine coolant temperature between 82°C - 101°C (180°F - 215°F) and the intake air temperature less than 46°C (115°F).
CAUTION: Do not clamp or pinch a hard plastic hose. Use a vacuum cap or equivalent to restrict the hose.
Note: Restricting the EVAP vapor hose while the EVAP emission canister is purging may shift the SHRTFT. Carry out a visual inspection as necessary.
Note: When monitoring for a decrease in the SHRTFT PIDs in the following steps, if SHRTFT1 equals +15% and the hose is restricted, SHRTFT1 decreases to -7%. The total decrease in the SHRTFT PIDs equals 22%.
Note: Address all continuous memory ignition and misfire DTCs before any KOER HO2S DTCs.
WARNING: WHEN CHECKING THE FUEL SYSTEM REMEMBER THAT THE FUEL SYSTEM MAY STILL BE PRESSURIZED WHEN THE ENGINE IS SWITCHED OFF. ALWAYS FOLLOW THE INSTRUCTIONS RELATED TO FUEL SYSTEM PRESSURE RELIEF. ALL FUEL HANDLING SAFETY PRECAUTIONS MUST BE OBSERVED.
Note: This step requires the use of a locally obtained 200 ml beaker and a 25 ml graduated cylinder.
Note: After approximately 3 minutes of standing, the ethanol and water mixes together and settles to the bottom of the 25 ml graduated cylinder. The gasoline rises to the top.
Note: Use the illustration as an example for calculating the percentage of ethanol in the following steps. If the separation level is at 14 ml the calculation becomes; 14 minus 4, then multiply by 5 to equal 50. The percentage of ethanol in the fuel is 50%.
Note: When determining if the FF PID value is within 50% of the calculated percentage of ethanol, if the calculated percentage of ethanol value is 40% then the PID value should be between 0 - 90%. The PID value cannot be less than zero.
Note: Certain customer fueling practices such as only fueling with small amounts of fuel or repeatedly switching between gasoline and an ethanol blend greater than E15 may prevent the PCM from learning the correct ethanol content in the fuel.
Note: Access the all INJF PIDs using a diagnostic tool.
Note: Continuous memory DTCs are erased during this test.
Note: Test all Fuel Injectors identified by DTC or PID interpretation.
Note: Disconnect the suspect fuel injector harness connector. Only the suspect injector needs to be diagnosed.
Note: An HO2S always lean condition can be caused by:
Note: Use the Misfire DTC(s) displayed or prior retrieval to determine which cylinder's compression to check.
Note: Fuel calculations can be affected by unmetered air leaks. DTC P2195 may result.
CAUTION: This test requires an observer to monitor the HO2S PID.
Note: Fuel calculations can be affected by unmetered air leaks.
Note: Any exhaust leaks between the engine and the output of the catalyst can cause DTCs P0136 or P0156.
Note: Address all other DTCs before proceeding. Engine at normal operating temperature.
Note: Sensor wiring swapped bank to bank.
Note: If DTCs are present, test their related circuits individually.