Page 1054 of 5267

Theory of Operation
The fuel feedback system will maintain a stoiciometric fuel/air mixture,14.7:1, by modifying the injector pulsewidth
according to the oxygen content of the exhaust gas. The PCM makes short termand long term fuel corrections to
maintain stoiciometric fuel/air ratio for best catalytic converter efficiency. 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:
With the engine running in closed loop mode, the ambient/battery temperature above 20 deg. F and altitude
below 8500 ft.
Set Condition:
If the PCM multiplies short term compensation by long term adaptive and a certain percentage is exceeded for
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 Causes
FUEL PRESSURE OUT OF SPECS
RESTRICTED FUEL SUPPLY LINE
FUEL PUMP INLET STRAINER PLUGGED
FUEL PUMP MODULE
O2 SENSOR
(K41) O2 SENSOR 1/1 SIGNAL CIRCUIT SHORTED TO GROUND
O2 SENSOR 1/1 HEATER OPERATION
TP SENSOR
MAP SENSOR
ECT SENSOR
ENGINE MECHANICAL CONDITION
FUEL FILTER/PRESSURE REGULATOR
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
Diagnostic Test
1.GOOD TRIP EQUAL TO ZERO
NOTE: Check for contaminates that may have damaged the O2 Sensor: contaminated fuel, unapproved sil-
icone, oil and coolant.
Ignition on, engine not running.
With the scan tool, read DTCs and record the related Freeze Frame data.
Is the Good Trip Counter displayed and equal to zero?
Ye s>>
Go To 2
No>>
Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
Page 1061 of 5267

Theory of Operation
The fuel feedback system will maintain a stoiciometric fuel/air mixture,14.7:1, by modifying the injector pulsewidth
according to the oxygen content of the exhaust gas. The PCM makes short termand long term fuel corrections to
maintain stoiciometric fuel/air ratio for best catalytic converter efficiency. 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:
With the engine running in closed loop mode, the ambient/battery temperature above 20 deg. F and altitude
below 8500 ft.
Set Condition:
If the PCM multiplies short term compensation by long term adaptive and a purge fuel multiplier and the result
is below a certain value for 30 seconds 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 Causes
O2 SENSOR
(K41) O2 SENSOR 1/1 SIGNAL CIRCUIT OPEN
(K41) O2 SENSOR 1/1 SIGNAL CIRCUIT SHORTED TO VOLTAGE
1/1 O2 SENSOR HEATER OPERATION
EVAP SYSTEM OPERATION
TP SENSOR VOLTAGE GREATER THAN 0.92 OF A VOLT WITH THROTTLE CLOSED
TP SENSOR
FUEL FILTER/PRESSURE REGULATOR
MAP SENSOR
ECT SENSOR
ENGINE MECHANICAL CONDITION
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
Diagnostic Test
1.GOOD TRIP EQUAL TO ZERO
NOTE: Check for contaminates that may have damaged the O2 Sensor: contaminated fuel, unapproved sil-
icone, oil and coolant.
Ignition on, engine not running.
With the scan tool, read DTCs and record the related Freeze Frame data.
NOTE: Any O2 Sensor, TPS, ECT, MAP, or EVAP DTCs must be repaired before continuing.
Is the Good Trip Counter displayed and equal to zero?
Ye s>>
Go To 2
No>>
Refer to the INTERMITTENT CONDITIONSymptom (Diagnostic Procedure).
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
Page 1067 of 5267

Theory of Operation
The fuel feedback system will maintain a stoiciometric fuel/air mixture,14.7:1, by modifying the injector pulsewidth
according to the oxygen content of the exhaust gas. The PCM makes short termand long term fuel corrections to
maintain stoiciometric fuel/air ratio for best catalytic converter efficiency. 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:
With the engine running in closed loop mode, the ambient/battery temperature above 20 deg. F and altitude
below 8500 ft.
Set Condition:
If the PCM multiplies short term compensation by long term adaptive and a certain percentage is exceeded for
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 Causes
FUEL PRESSURE OUT OF SPECS
RESTRICTED FUEL SUPPLY LINE
FUEL PUMP INLET STRAINER PLUGGED
FUEL PUMP MODULE
O2 SENSOR
(K43) O2 SENSOR 2/1 SIGNAL CIRCUIT SHORTED TO GROUND
O2 SENSOR 2/1 HEATER OPERATION
TP SENSOR
MAP SENSOR
ECT SENSOR
ENGINE MECHANICAL CONDITION
FUEL FILTER/PRESSURE REGULATOR
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
Diagnostic Test
1.GOOD TRIP EQUAL TO ZERO
NOTE: Check for contaminates that may have damaged the O2 Sensor: contaminated fuel, unapproved sil-
icone, oil and coolant.
Ignition on, engine not running.
With the scan tool, read DTCs and record the related Freeze Frame data.
Is the Good Trip Counter displayed and equal to zero?
Ye s>>
Go To 2
No>>
Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
Page 1074 of 5267

Theory of Operation
The fuel feedback system will maintain a stoiciometric fuel/air mixture,14.7:1, by modifying the injector pulsewidth
according to the oxygen content of the exhaust gas. The PCM makes short termand long term fuel corrections to
maintain stoiciometric fuel/air ratio for best catalytic converter efficiency. 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:
With the engine running in closed loop mode, the ambient/battery temperature above 20 deg. F and altitude
below 8500 ft.
Set Condition:
If the PCM multiplies short term compensation by long term adaptive and a purge fuel multiplier and the result
is below a certain value for 30 seconds 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 Causes
O2 SENSOR
(K43) O2 SENSOR 2/1 SIGNAL CIRCUIT OPEN
(K43) O2 SENSOR 2/1 SIGNAL CIRCUIT SHORTED TO VOLTAGE
2/1 O2 SENSOR HEATER OPERATION
EVAP SYSTEM OPERATION
TP SENSOR VOLTAGE GREATER THAN 0.92 OF A VOLT WITH THROTTLE CLOSED
TP SENSOR
FUEL FILTER/PRESSURE REGULATOR
MAP SENSOR
ECT SENSOR
ENGINE MECHANICAL CONDITION
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
Diagnostic Test
1.GOOD TRIP EQUAL TO ZERO
NOTE: Check for contaminates that may have damaged the O2 Sensor: contaminated fuel, unapproved sil-
icone, oil and coolant.
Ignition on, engine not running.
With the scan tool, read DTCs and record the related Freeze Frame data.
NOTE: Any O2 Sensor, TPS, ECT, MAP, or EVAP DTCs must be repaired before continuing.
Is the Good Trip Counter displayed and equal to zero?
Ye s>>
Go To 2
No>>
Refer to the INTERMITTENT CONDITIONSymptom (Diagnostic Procedure).
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
Page 1079 of 5267
P0197-ENGINE OIL TEMPERATURE SENSOR VOLTAGE TOO LOW
For a complete wiring diagramRefer to Section 8W.
Page 1080 of 5267

When Monitored:
Ignition on.
Set Condition:
When the PCM recognizes the engine oil temperature sensor signal goes below a specific value.
Possible Causes
ENGINE OIL TEMP SENSOR
(G127) ENGINE OIL TEMP SENSOR SIGNAL CIRCUIT SHORTED TO GROUND
(G127) ENGINE OIL TEMP SENSOR CIRCUIT SHORTED TO THE (Z1) GROUND CIRCUIT
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
1.EOT VOLTAGE BELOW 1.0 VOLT
Ignition on, engine not running.
With the scan tool, read DTCs and record the related Freeze Frame data.
With the scan tool, read the Engine Oil Temp Sensor voltage.
Is the EOT Sensor voltage below 1.0 volt?
Ye s>>
Go To 2
No>>
Refer to the INTERMITTENT CONDITIONSymptom (Diagnostic Procedure).
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
2.ENGINE OIL TEMP SENSOR
Turn the ignition off.
Disconnect the Engine Oil Temp harness connector.
Ignition on, engine not running.
With the scan tool, read Engine Oil Temp voltage.
Is the voltage above 1.0 volt?
Ye s>>
Replace the Engine Oil Temp Sensor.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 3
3.(G127) EOT SENSOR SIGNAL CIRCUIT SHORTED TO GROUND
Turn the ignition off.
Disconnect the PCM harness connectors.
Measure the resistance between ground and the (G127) Engine Oil
Temp Sensor Signal circuit at the EOT Sensor harness connector.
Istheresistancebelow100ohms?
Ye s>>
Repair the short to ground in the (G127) Engine Oil Temp
Sensor Signal circuit.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 -
ENGINE - STANDARD PROCEDURE)
No>>
Go To 4
Page 1082 of 5267
P0198-ENGINE OIL TEMPERATURE SENSOR VOLTAGE TOO HIGH
For a complete wiring diagramRefer to Section 8W.
Page 1083 of 5267

When Monitored:
Ignition on.
Set Condition:
When the PCM recognizes the engine oil temperature sensor signal above a specific voltage.
Possible Causes
ENGINE OIL TEMP SENSOR
(G127) ENGINE OIL TEMP SENSOR SIGNAL CIRCUIT SHORTED TO VOLTAGE
(G127) ENGINE OIL TEMP SENSOR SIGNAL CIRCUIT OPEN
(Z1) GROUND CIRCUIT OPEN
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
1.ENGINE OIL TEMP VOLTAGE ABOVE 4.9 VOLTS
Ignition on, engine not running.
With the scan tool, read DTCs and record the related Freeze Frame data.
With the scan tool, read Engine Oil Temp Sensor voltage.
Is the voltage above 4.9 volts?
Ye s>>
Go To 2
No>>
Refer to the INTERMITTENT CONDITIONSymptom (Diagnostic Procedure).
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
2.ENGINE OIL TEMP SENSOR
Turn the ignition off.
Disconnect the Engine Oil Temp Sensor harness connector.
Ignition on, engine not running.
Connect a jumper wire between the (G127) Engine Oil Temp Sensor
Signal circuit and the (Z1) ground circuit in the EOT harness connector.
With the scan tool, read the Engine Oil Temp Sensor voltage.
Is the voltage below 1.0 volt?
Ye s>>
Replace the Engine Oil Temp Sensor.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 -
ENGINE - STANDARD PROCEDURE)
No>>
Go To 3
NOTE: Remove the jumper wire before continuing.