Suzuki XL7 2007 Service Manual page 198

1A-93 Engine General Information and Diagnosis:
Circuit Description
The heated oxygen sensor (HO2S) heater reduces the
time required for the oxygen sensor to reach operating
temperature and maintains the operating temperature
during extended idle periods. When the ignition is turned
to the ON position, ignition voltage is supplied directly to
the sensor heater. The engine control module (ECM)
controls the heater operation by first modulating the
control circuit to ground when the sensors are cold. This
prevents the possibility of thermal shock to the sensor,
from condensation build-up on the sensor, by controlling
the sensor's rate of heating. After a predetermined
amount of time, the ECM commands the heaters ON
continuously. Once the sensor reaches operating
temperature, the ECM may modulate the heater control
circuit to ground to maintain a desired temperature. The
ECM controls the heater by grounding the control circuit
with a solid state device called a driver. The driver is
equipped with a feedback circuit that is pulled up to
voltage. The ECM can determine if the control circuit is
open, shorted to ground, or shorted to a voltage by
monitoring the feedback voltage.
Conditions for Running the DTC
P0135 or P0155
• Before the ECM can report DTC P0135 or P0155
failed, P0030, P0031, P0032, P0050, P0051, and
P0052 must run and pass.
• DTCs P0131, P0132, P0134, P0151, P0152, and
P0154 are not set.
• The engine is operating.
• The ignition voltage is 10.5-18.1 volts.
• The intake air temperature (IAT) is greater than −30°C
(−22°F).
• After the previous ignition cycle the engine OFF time
was greater than 2 minutes.
• The calculated exhaust temperature is less than
500°C (932°F).
• The engine is not in decel fuel cut-off (DFCO).
• The HO2S is at operating temperature for greater
than 10 seconds.
• The internal HO2S resistance is less than 10,000
ohms.
• DTCs P0135 and P0155 run continuously once the
above conditions are met for approximately 100
seconds.
P0141 or P0161
• Before the ECM can report DTC P0141 or P0161
failed, DTCs P0036, P0037, P0038, P0056, P0057,
and P0058 must run and pass.
• DTCs P0137, P0138, P0140, P0157, P0158, or
P0160 are not set.
• The engine is operating.
• The ignition voltage is 10.5-18.1 volts.
• The intake air temperature (IAT) is greater than −30°C
(−22°F).
• After the previous ignition cycle the engine OFF time
was greater than 2 minutes.
• The calculated exhaust temperature is 360-500°C
(680-932°F).
• The engine is not in decel fuel cut-off (DFCO).
• The internal HO2S resistance is less than 10,000
ohms.
• DTCs P0141 and P0161 run continuously once the
above conditions are met for approximately 100
seconds.
Conditions for Setting the DTC
The ECM detects that the internal resistance of a
primary or secondary HO2S heater is not within the
expected range for more than 4 seconds or for a
cumulative of 50 seconds.
Action Taken When the DTC Sets
DTCs P0135, P0141, P0155, and P0161 are Type B
DTCs.
Conditions for Clearing the MIL/DTC
DTCs P0135, P0141, P0155, and P0161 are Type B
DTCs.
Reference Information
Schematic Reference
"Engine Controls Schematics"
Connector End View Reference
• "Engine Control Module Connector End Views"
• "Engine Controls Connector End Views"
Electrical Information Reference
• "Circuit Testing: "
• "Connector Repairs: "
• "Testing for Intermittent Conditions and Poor
Connections: "
• "Wiring Repairs: "
DTC Type Reference
"Powertrain Diagnostic Trouble Code (DTC) Type
Definitions"
Scan Tool Reference
• "Scan Tool Data List - Engine Controls - 3.6L (LY7)"
• "Scan Tool Data Definitions - Engine Controls - 3.6L
(LY7)"
• "Scan Tool Output Controls - Engine Controls - 3.6L
(LY7)"