For a complete wiring diagram, refer to the Wiring Information.
Theory of Operation
The fuel feedback system will maintain a stoichiometric air/fuel mixture, 14.7:1, by modifying the injector pulsewidth according to the oxygen content of the exhaust gas. The Powertrain Control Module (PCM) makes short term and long term fuel corrections to maintain stoiciometric air/fuel ratio for best Catalytic Converter efficiency. If one or more cylinders do not operate at stoichiometric then the high frequence content of the O2 Sensor will increase. Short term fuel correction is based on Upstream O2 Sensor output and is designed for quick engine response. The long term fuel correction compensated for variations in the engine specifications, sensor tolerances and component aging and is designed to correct rich and lean conditions over a longer period of time.
When Monitored:
Engine Coolant Temperature (ECT) is greater than 70°C (158°F), Engine run time of 90 seconds, engine RPM 1000 - 2700, engine load 30 - 90% and in flex fuel vehicles the Fuel Adaptive Learned must be completed.
Set Condition:
DTC P113E is not set and the high frequency content of the O2 Sensor exceeds a calibrated amount. Two Trip Fault. Three good trips to turn off the MIL.
Check for contaminates that may have damaged an O2 Sensor: contaminated fuel, unapproved silicone, oil and coolant.
1.
Start the engine.
2.
Allow the engine to reach normal operating temperature.
3.
With the scan tool, read DTCs.
NOTE:
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.
The fuel system is under a constant
pressure (even with the engine off). Before testing or servicing any
fuel system hose, fitting or line, the fuel system pressure must be
released. Failure to follow these instructions can result in possible
serious or fatal injury.
1.
Turn the ignition off.
2.
Install the Fuel Pressure Decay Tester
8978A
to the fuel rail.
3.
Ignition on, engine not running.
4.
Using the scan tool, actuate the Fuel System test and observe the fuel pressure gauge.
Allow the engine to reach normal operating temperature.
NOTE:
If one of the O2 Sensors Signal or Return circuit is shorted to ground or voltage, all the other O2 Sensor voltage readings will be affected.
NOTE:
After the repairs have been made, verify proper O2 Sensor operation. If all the O2 Sensor voltage readings have not returned to normal, follow the diagnostic procedure for the remaining O2 Sensors.
3.
Using the scan tool, monitor the O2 Sensor 2/1 voltage reading.
Is the voltage switching between 2.5 and 3.4 Volts?
Wait a minimum of 10 minutes to allow the O2 Sensor to cool down before continuing the test. Allow the O2 Sensor voltage to stabilize at 5.0 Volts.
2.
Ignition on, engine not running.
3.
Using the scan tool, perform the O2 Sensor 2/1 Heater Test for each O2 Sensor.
4.
Using the scan tool, monitor the O2 Sensor 2/1 voltage while performing the Heater test for at least two minutes.
Does the voltage stay above 4.5 Volts for each Sensor?
Yes
Verify that there is good pin to terminal contact in the O2 Sensor and Powertrain Control Module connectors. Replace the O2 Sensor if no problems were found with the connectors.
The Barometric Pressure should be approximately equal to the actual barometric pressure. If necessary, compare the Barometric Pressure value of this vehicle to the value of a known good vehicle of a similar make and model.
3.
Turn the ignition off.
4.
Connect a Vacuum Gauge to a Manifold Vacuum source.
5.
Start the engine.
6.
Allow the engine to idle.
NOTE:
If engine will not idle, maintain a constant RPM above idle.
7.
Using the scan tool, read the MAP Sensor vacuum value.
Is the scan tool reading for MAP Vacuum within 1" of Hg on the Vacuum Gauge reading and is the Barometric Pressure reading of the vehicle the approximately the same as actual Barometric Pressure?
Verify that there is good pin to terminal contact in the MAP Sensor and Powertrain Control Module connectors. Replace the MAP Sensor if no problems were found with the connectors.
For this test to be valid, the thermostat must be operating correctly.
NOTE:
This test works best if performed on a cold engine (cold soak).
1.
Ignition on, engine not running.
2.
Using the scan tool, read the Engine Coolant Temperature Sensor value. If the engine was allowed to sit overnight (cold soak), the temperature value should be a sensible value that is somewhere close to the ambient temperature.
NOTE:
If engine coolant temperature is above 82°C (180°F), allow the engine to cool until 65°C (150°F) is reached.
3.
Start the Engine.
4.
During engine warm-up, monitor the Engine Coolant Temperature value. The temp value change should be a smooth transition from start up to normal operating temp 82°C (180°F). The value should reach at least 82°C (180°F).
Did the ECT value increase smoothly and reach at least 82°C (180°F)?
Verify that there is good pin to terminal contact in the ECT Sensor and Powertrain Control Module connectors. Replace the Engine Coolant Temperature Sensor if no problems were found with the connectors.
Verify that there is good pin to terminal contact in the Evap Purge Solenoid and Powertrain Control Module connectors. Replace the Evap Purge Solenoid if no problems were found with the connectors.
Using the scan tool, monitor the O2 Sensor 2/1 voltage.
4.
O2 Sensor voltage should read between 4.1 and 5.0 Volts on the scan tool with the connector disconnected.
5.
Connect a jumper wire between the (K43) O2 Sensor 2/1 Signal circuit and the (K902) O2 Sensor 2/1 Return circuit in the O2 Sensor harness connector.
NOTE:
The voltage should drop from between 4.1 and 5.0 Volts down to 2.5 Volts with the jumper wire connected.
Did the O2 Sensor voltage drop from between 4.1 and 5.0 Volts to 2.5 Volts when the jumper wire was installed?
Yes
Verify that there is good pin to terminal contact in the O2 Sensor and Powertrain Control Module connectors. Replace the O2 Sensor if no problems were found with the connectors. .
Check the (K43) O2 Sensor 2/1 Signal circuit for damage, 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 in accordance with the Service Information.
Check the (K902) O2 Sensor 2/1 Return circuit for damage, 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 in accordance with the Service Information.
