P2097-DOWNSTREAM FUEL TRIM SYSTEM 1 RICHFor a complete wiring diagram Refer to Section 8W.When Monitored:With the engine running in closed loop mode, the ambient/battery temperature above -6.7°C (20°F)
and altitude below 2590.8 m (8500 ft).Set Condition:If the PCM multiplies short term compensation by long term adaptive as well as a purge fuel multiplier and the result is below a certain value for a calibrated amount of time over two trips, a freeze
frame is stored, the MIL illuminates and a trouble code is stored. Two Trip Fault. Three good trips to turn off the MIL.
Possible CausesEXHAUST LEAKENGINE MECHANICAL1/2 O2 SENSOR(K141) O2 1/2 SIGNAL CIRCUIT(K299) O2 HEATER 1/2 CONTROL CIRCUIT(K904) O2 RETURN DOWNSTREAM CIRCUITFUEL CONTAMINATION
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).Diagnostic Test1.ACTIVE DTCCheck the vehicle repair history. If the 1/2 O2 has been replaced make sure that the O2 sensor was properly installed and meets OEM specification.Check for contaminants that may have damaged the O2 Sensor: contaminated fuel, unapproved silicone, oil and coolant.Start the engine.Allow the engine to reach normal operating temperature.With a scan tool, select View DTCs.It may be necessary to drive the vehicle to meet the conditions to set this DTC, try to repeat the conditions in which the fault originally set by reviewing the Freeze
Frame data.Is the DTC Active or Pending at this time?YesGo To 2NoRefer to the INTERMITTENT CONDITION Diagnostic Procedure.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)2.CHECKING THE EXHAUST SYSTEM FOR LEAKSTurn the ignition off.Raise the vehicle in accordance with the Service Information.The normal operating temperature of the exhaust system is very high. Never work around or attempt to service any part of the exhaust system until it has cooled. Special
care should be taken when working near the catalytic converter. The temperature of the converter rises to a high level after a short period of engine operating timeConnect Exhaust Cone #8404-EC or #8404–EC to Air Pressure Regulator (with hose) #W-18-MIL-1146AS.The air pressure must not exceed 27.6 kPa (4 psi), otherwise engine damage can occur.Attach shop air to the air pressure regulator.Adjust the Air Pressure Regulator to 27.6 kPa (4 psi)Insert the exhaust cone into the vehicle tail pipe.If the vehicle is equipped with dual exhaust. Use the #8404-ECT with equipped attached plug, plug one side of the dual exhaust pipe. Pressurize the other as described above.Apply SNOOP leak finder liquid or a mixture of liquid dish soap and water to the following areas: - All welded joints from the exhaust manifold to 152.4 mm (6 inches) behind the downstream O2 sensor - O2 sensor seal points - O2 sensor boss welds - Flange/joint connection(s) - Exhaust manifold to cylinder head connection(s) - EGR solenoid gasket base and tube seal points (if equipped)Watch for the liquid/soapy water to bubble.Use the following definitions to help determine if system or component repair/replacement is necessary:Type 1 Leak is defined as a leak where very small foam like bubbles 1 mm (0.04 of an inch) or less appear.Any Type 1 or greater leaks found in welded joints, O2 sensor seal points or O2 sensor boss welds must be repaired or the component must be replaced.Type 2 Leak is defined as a leak where larger bubbles pea size, 8 mm (0.3 of an inch) or greater appear.Any Type 2 or greater leaks found in flange or joint connections, exhaust manifold to cylinder head connections, or EGR gasket and tube seal points must be repaired or the components must be
replaced
Leak LocationRepair required if results at 27.6 kPa (4 psi) reveal bubble size:Welded jointsType 1, 1 mm (0.04 of an inch) or greaterO2 Sensor seal pointsType 1, 1 mm (0.04 of an inch) or greaterO2 Sensor boss weldsType 1, 1 mm (0.04 of an inch) or greaterFlange / joint connectionsType 2, 8 mm (0.3 of an inch) or greaterExhaust Manifold to cylinder head connectionsType 2, 8 mm (0.3 of an inch) or greaterEGR gasket and tube seal pointsType 2, 8 mm (0.3 of an inch) or greater
If a leak is found that matches the above definition, repair or replace the component as necessary.Once the repair is complete, repeat the procedure to verify that all leaks have been repaired.Were any exhaust leaks found?YesRepair or replace the leaking exhaust parts as necessary.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)NoGo To 33.ENGINE MECHANICALCheck for any of the following conditions/mechanical problemsAIR INDUCTION SYSTEM - must be free from leaks.ENGINE VACUUM - must be at least 13 inches in neutralENGINE VALVE TIMING - must be within specificationsENGINE COMPRESSION - must be within specificationsENGINE EXHAUST SYSTEM - must be free of any restrictions or leaksENGINE PCV SYSTEM - must flow freelyTORQUE CONVERTER STALL SPEED - must be within specificationsPOWER BRAKE BOOSTER - no internal vacuum leaksFUEL - must be free of contaminationFUEL INJECTOR - plugged or restricted injector; control wire not connected to correct injectorAre there any engine mechanical problems?YesRepair as necessary.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)NoGo To 44.O2 SENSORIgnition on, engine not running.Disconnect the 1/2 O2 Sensor harness connector.With the scan tool, monitor the 1/2 O2 Sensor voltage.The O2 Sensor voltage should read 5.0 volts on the scan tool with the connector disconnected.Using a jumper wire, jump the (K141) O2 Sensor 1/2 Signal circuit to the (K904) O2 Return Downstream circuit in the O2 Sensor harness connector.The voltage should drop from 5.0 volts to 2.5 volts with the jumper wire in place.Did the O2 Sensor volts change from 5.0 volts to 2.5 volts?YesReplace the O2 SensorPerform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)NoGo To 55.(K141) O2 SENSOR 1/2 SIGNAL CIRCUITRemove the jump wire.Ignition on, engine not running.With the scan tool, monitor the 1/2 O2 Sensor voltage.Is the voltage above 4.8 volts?YesGo To 6NoCheck the (K141) O2 Sensor 1/2 Signal circuit for an open or short to voltage. Inspect the O2 Sensor connector and the PCM harness connector. If OK, replace
and program the Powertrain Control Module per Service Information.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)6.(K299) O2 SENSOR 1/2 HEATER CONTROL CIRCUIT OPENTurn the ignition off.Disconnect the C3 PCM harness connector.Measure the resistance of the (K299) O2 Sensor 1/2 Heater Control circuit from the O2 Sensor harness connector to the appropriate terminal of special tool #8815.Is the resistance below 5.0 ohms?Yes Go To 7No Repair the open in the (K299) O2 Sensor 1/2 Heater Control circuit.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)7.(K904) O2 RETURN DOWNSTREAM CIRCUITMeasure the voltage on the (K904) O2 Return Downstream circuit in the O2 Sensor harness connector.Is the voltage at 2.5 volts?YesCheck the fuel system for contaminants.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)NoCheck the (K904) O2 Return Downstream circuit for a short to ground, open, or short to voltage. Inspect the O2 Sensor connector and the PCM harness connector.
If OK, replace and program the Powertrain Control Module per Service Information.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)