Suzuki XL7 2007 Service Manual page 270

1A-165 Engine General Information and Diagnosis:
Circuit/System Verification
1. Start the engine. Observe the DTC information with a
scan tool. DTCs P2227, P2228, or P2229 should not
set.
2. If the vehicle passes the Circuit/System Verification
test, then operate the vehicle within the conditions
for running the DTC. You may also operate the
vehicle within the conditions that are captured in the
Freeze Frame/Failure Records Data List.
Circuit/System Testing
1. Inspect the atmospheric vent on the ECM case for
one of the following conditions:
– Moisture in the vent inlet
– Debris in the vent inlet
➢ If a condition exists, attempt to clean or dry the
atmospheric inlet.
2. Start the engine. Observe the DTC information with a
scan tool. DTCs P2227, P2228, or P2229 should not
set.
➢ If DTC P2227, P2228, or P2229 sets, replace the
ECM.
Repair Instructions
Perform the "Diagnostic Repair Verification - Vehicle
Diagnostic Information: " after completing the diagnostic
procedure.
"Control Module References: " for engine control module
replacement, setup, and programming
DTC P2231 or P2234
Diagnostic Instructions
• Perform the "Diagnostic System Check - Vehicle
Diagnostic Information: " prior to using this diagnostic
procedure.
• Review "Strategy Based Diagnosis: " for an overview
of the diagnostic approach.
• "Diagnostic Procedure Instructions - Vehicle
Diagnostic Information: " provides an overview of
each diagnostic category.
DTC Descriptors
DTC P2231: HO2S Signal Circuit Shorted to Heater
Circuit Bank 1 Sensor 1
DTC P2234: HO2S Signal Circuit Shorted to Heater
Circuit Bank 2 Sensor 1
Circuit Description
The engine control module (ECM) supplies a voltage
near 450 mV between the heated oxygen sensor
(HO2S) signal circuit and the low reference circuit. The
HO2S varies the voltage over a range from about 1,000
mV when the exhaust is rich, down through about 10 mV
when the exhaust is lean. The ECM monitors and stores
the HO2S voltage information. The ECM evaluates the
HO2S voltage samples in order to determine the amount
of time that the HO2S voltage was out of range. Or, to
detect if the HO2S signal voltage switches at the same
rate at which the ECM is commanding the heater ON
and OFF.
Conditions for Running the DTC
• Before the ECM can report that DTC P2231 or P2234
failed, DTCs P0030, P0031, P0032, P0050, P0051,
P0052, P0133, P0135, P0153, and P0155 must run
and pass.
• DTCs P0030, P0031, P0032, P0050, P0051, P0052,
P0116, P0117, P0118, P0119, P0125, P0133, P0135,
P0153, P0155, P0201, P0202, P0203, P0204, P0205,
P0206, P0261, P0262, P0264, P0265, P0267, P0268,
P0270, P0271, P0273, P0274, P0276, and P0277 are
not set.
• The engine is operating.
• The ignition voltage is greater than 10 volts.
• The calculated exhaust gas temperature is between
600-800°C (1,112-1,472°F).
• The engine coolant temperature (ECT) during the
previous ignition cycle was greater than 60°C (140°F).
• The ECT at engine start is less than 40°C (104°F).
• The HO2S heater control is enabled for greater than 5
seconds.
• DTC P2231 and P2234 run continuously once the
conditions above exist for greater than 90 seconds.
Conditions for Setting the DTC
DTC P2231 or P2234 will set when any of the following
conditions exist:
• The ECM detects that the HO2S signal voltage
increases more than 2 volts in 4 out of 6 HO2S heater
switch OFF samples.
• The primary HO2S voltage is between 600-1,008 mV
and the corresponding secondary HO2S voltage is
less than 100 mV for greater than 4 seconds or for a
cumulative of 50 seconds.
• The primary HO2S voltage is between 60-400 mV and
the corresponding secondary HO2S voltage is less
than 500 mV for greater than 4 seconds or for a
cumulative of 50 seconds.