Suzuki XL7 2007 Service Manual page 275

DTC P2271 or P2273
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 P2271: HO2S Signal Stuck Rich Bank 1 Sensor 2
DTC P2273: HO2S Signal Stuck Rich Bank 2 Sensor 2
Circuit Description
The engine control module (ECM) supplies a voltage
near 450 mV between the heated oxygen sensor
(HO2S) high 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. The ECM compares the stored HO2S
voltage samples taken within each sample period and
determines if the majority of the samples are out of the
operating range. The ECM test for the following
conditions:
• The ECM monitors the HO2S voltage to determine if
the signal voltage goes below a predetermined
threshold within a certain amount of time. If the ECM
determines that the signal voltage remains above the
threshold, the ECM will command the fuel system
lean to determine if the HO2S signal voltage can be
forced below the threshold within a certain amount of
time.
• The ECM monitors the HO2S voltage during fuel cut-
off to determine if the signal voltage is more than a
predetermined threshold.
Engine General Information and Diagnosis:
Conditions for Running the DTC
• Before the ECM can report DTC P2270 or P2272
failed, DTCs P0036, P0037, P0038, P0056, P0057,
P0058, P0137, P0138, P0140, P0141, P0157, P0158,
P0160, P0161, P0341, P0342, P0343, P0346, P0347,
P0348, P0366, P0367, P0368, P0391, P0392, P0393,
P0443, P0458, and P0459 must run and pass.
• DTCs P0461, P0462, P0463, P2066, P2067, and
P2068 are not set.
• The engine is operating.
• The ignition voltage is greater than 10 volts.
• The rear HO2S are at operating temperature for more
than 10 seconds.
• The fuel injectors are enabled.
• The long term fuel control is enabled.
• The mass air flow (MAF) sensor is more than 10 g/s.
• The MAF sensor is between 6-33 g/s for more than 3
seconds during the intrusive test.
• The accumulated air flow into the engine is more than
15 grams during the fuel cut-off event.
• DTC P2271 and P2273 runs continuously once the
above conditions are met.
Conditions for Setting the DTC
The ECM detects that the rear HO2S voltage is more
than 650 mV for more than 100 seconds, then an
intrusive test is performed. The ECM will lean the fuel
mixture up to −7 percent and then wait for 10 seconds at
−7 percent. If the ECM detects that the HO2S voltage is
still more than 650 mV, the ECM then tests the HO2S at
the next decel fuel cut-off. If the ECM detects the HO2S
voltage is more than 200 mV after 4 seconds or for a
cumulative of 50 seconds in decel fuel cut-off, the DTC
sets.
Action Taken when the DTC Sets
DTCs P2271 and P2273 are Type B DTCs.
Conditions for Clearing the MIL/DTC
DTCs P2271 and P2273 are Type B DTCs.
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