Workshop Manual

6E–161
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC)
P0125 ECT Excessive Time to Closed Loop Fuel Control
060R200053
Circuit Description
To provide the best possible combination of driveability,
fuel economy, and emission control, a “closed loop”
air/fuel metering system is used. When the vehicle is first
started, the powertrain control module (PCM) controls
fuel delivery in “open loop”, ignoring the heated oxygen
sensor (HO2S) signals and calculating air/fuel ratio based
on inputs from the engine coolant temperature, throttle
position, and mass air flow sensors. The PCM will begin
using the Bank 1 HO2S 1 and Bank 2 HO2S 1 signals for
controlling fuel delivery under “closed loop” conditions
when the following conditions have been met:
B The HO2S output signals are varying, indicating that
the sensors are hot enough to operate properly.
B The engine coolant temperature sensor indicates
coolant temperature above 50°C (122°F).
B Time since start-up is at least 16 seconds for a warm
engine or 23 seconds for a cold engine.
Conditions for Setting the DTC
B No active IAT, MAF or ECT DTC(s) are present.
B Engine is running.
B Vehicle speed is greater than 5 mph (8 km/h) .
B Intake air temperature is greater than –10°C (14°F)
0°C (32°F).
B Start–up engine coolant temperature is between
–10°C (–14°F) and 28°C (82°F).
B For a warm engine (intake air temperature is greater
than 10°C/50°F), engine coolant temperature
sufficient to allow “closed loop” operation
(50°C/122°F) is not achieved within 2 minutes of
start-up. For a cold engine (intake air temperature
between (–7°C and 10°C), engine coolant
temperature sufficient to allow “closed loop” operation
(50°C/122°F) is not achieved within 10 minutes of
start-up.
B The above condition fails 20 consecutive times.
Action Taken When the DTC Sets
B The PCM will ON the MIL after second trip with
detected fault.
B The PCM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.
Conditions for Clearing the MIL/DTC
B The PCM will turn the MIL “OFF” on the third
consecutive trip cycle during which the diagnostic has
been run and the fault condition is no longer present.
B A history DTC P0125 will clear after 40 consecutive
warm-up cycles have occurred without a fault.
B DTC P0125 can be cleared by using the Tech 2 “Clear
Info” function or by disconnecting the PCM battery
feed.