oxygen SUZUKI SX4 2006 1.G Service User Guide

Downloaded from www.Manualslib.com manuals search engine Engine General Information and Diagnosis: 1A-41
Scan Tool Data Definitions
COOLANT TEMP (ENGINE COOLANT
TEMPERATURE, °C, °F)
It is detected by engine coolant temp. sensor.
INTAKE AIR TEMP. (°C, °F)
It is detected by intake air temp. sensor.
ENGINE SPEED (rpm)
It is computed by reference pulses from the camshaft
position sensor.
DESIRED IDLE (DESIRED IDLE SPEED, rpm)
The Desired Idle Speed is an ECM internal parameter
which indicates the ECM requested idle. If the engine is
not running, this number is not valid.
MAF (MASS AIR FLOW RATE, g/s, lb/min.)
It represents total mass of air entering intake manifold
which is measured by mass air flow sensor.
CALC LOAD (CALCULATED LOAD VALUE, %)
Engine load displayed as a percentage of maximum
possible load. Value is calculated mathematically using
the formula: actual (current) intake air volume ÷
maximum possible intake air volume × 100%
MAP (MANIFOLD ABSOLUTE PRESSURE, in.Hg,
kPa)
This value indicates how much correction is necessary
to keep the air/fuel mixture stoichiometrical.
It is detected by manifold absolute pressure sensor.
THROTTLE POS (RELATIVE THROTTLE POSITION,
%)
When throttle position sensor is at fully closed position,
throttle opening is indicated as 0 – 12% and 90 – 100%
full open position.
BAROMETRIC PRESS (kPa, in.Hg)
This parameter represents a measurement of barometric
air pressure and is used for altitude correction of the fuel
injection quantity.
FUEL TANK LEVEL (%)
This parameter indicates approximate fuel level in fuel
tank. As detectable range of fuel level sensor is set as 0
to 100%, however, with some models whose fuel tank
capacity is smaller, indicated fuel level may be only 70%
even when fuel tank is full.
BATTERY VOLTAGE (V)
This parameter indicates battery positive voltage
inputted from main relay to ECM.
BRAKE SW (ON/OFF)
This parameter indicates the state of the brake switch.FUEL SYSTEM B1 (FUEL SYSTEM STATUS)
Air/fuel ratio feedback loop status displayed as one of
the followings.
OPEN: Open-loop has not yet satisfied conditions to go
closed loop.
CLOSED: Closed-loop using oxygen sensor(s) as
feedback for fuel control.
OPEN-DRIVE COND: Open-loop due to driving
conditions (Power enrichment, etc.).
OPEN SYS FAULT: Open-loop due to detected system
fault.
O2S SENSOR B1 S1 (HEATED OXYGEN SENSOR-1,
V)
It indicates output voltage of HO2S-1 installed on
exhaust manifold (pre-catalyst.)
O2S SENSOR B1 S2 (HEATED OXYGEN SENSOR-2,
V)
It indicates output voltage of HO2S-2 installed on
exhaust pipe (post-catalyst). It is used to detect catalyst
deterioration.
SHORT FT B1 (SHORT TERM FUEL TRIM, %)
Short term fuel trim value represents short term
corrections to the air/fuel mixture computation. A value
of 0 indicates no correction, a value greater than 0
means an enrichment correction, and a value less than 0
implies an enleanment correction.
LONG FT B1 (LONG TERM FUEL TRIM, %)
Long term fuel trim value represents long term
corrections to the air/fuel mixture computation. A value
of 0 indicates no correction, a value greater than 0
means an enrichment correction, and a value less than 0
implies an enleanment correction.
TOTAL FUEL TRIM B1 (%)
The value of Total Fuel Trim is obtained by calculating
based on values of Short Term Fuel Trim and Long Term
Fuel Trim. This value indicates how much correction is
necessary to keep the air/fuel mixture stoichiometrical.
FUEL CUT (ON/OFF)
ON: Fuel being cut (output signal to injector is stopped)
OFF: Fuel not being cut
O2S B1 S2 ACT (HEATED OXYGEN SENSOR-2,
ACTIVE / INACTIVE)
This parameter indicates activation condition of HO2S-2
ACTIVE: Activating
INACTIVE: warming up or at stop
O2S B1 S1 ACT (HEATED OXYGEN SENSOR-1,
ACTIVE / INACTIVE)
This parameter indicates activation condition of HO2S-1
ACTIVE: Activating
INACTIVE: warming up or at stop

Downloaded from www.Manualslib.com manuals search engine 1A-60 Engine General Information and Diagnosis:
2HO2S-1 heater power circuit check
1) Disconnect connector from HO2S-1 with ignition switch
turned OFF.
2) Check for proper connection to HO2S-1 at “BLK/WHT”
and “BLK/RED” wire terminals.
3) If wire and connection are OK, measure voltage
between “BLK/WHT” wire terminal and engine ground
with ignition switch turned ON.
Is voltage over 10 V?Go to Step 3. “BLK/WHT” wire is open
circuit or shorted to
ground circuit.
3HO2S-1 heater power circuit check
1) Disconnect connectors from ECM with ignition switch
turned OFF.
2) Measure resistance between “BLK/WHT” wire terminal
of HO2S-1 connector and “E01-29” terminal of ECM
connector.
Is resistance below 5
Ω?Go to Step 4. “BLK/WHT” wire is high
resistance circuit.
4HO2S-1 heater drive circuit check
1) Measure resistance between “C01-46” terminal of ECM
connector and vehicle body ground.
Is resistance infinity?Go to Step 5. “BLK/RED” wire is
shorted to ground
circuit.
5HO2S-1 heater drive circuit check
1) Turn ON ignition switch.
2) Measure voltage between “C01-46” terminal of ECM
connector and vehicle body ground.
Is voltage 0 V?Go to Step 6. “BLK/RED” wire is
shorted to power circuit.
6HO2S-1 heater drive circuit check
1) Connect connector to HO2S-1 with ignition switch turned
OFF.
2) Turn ON ignition switch.
3) Measure voltage between “C01-46” terminal of ECM
connector and vehicle body ground with connector
disconnected from ECM.
Is voltage over 10 V?Go to Step 7. “BLK/RED” wire is open
circuit.
7HO2S-1 heater check
1) Disconnect HO2S-1 connector with ignition switch
turned OFF.
2) Check HO2S-1 heater resistance referring to “Heated
Oxygen Sensor (HO2S-1 and HO2S-2) Heater On-
Vehicle Inspection (If Equipped) in Section 1C”.
Is resistance within specified value range?Go to Step 8. Replace HO2S-1.
8HO2S-1 heater power circuit check
1) Connect connector to HO2S-1 with ignition switch turned
OFF.
2) Measure resistance between “E01-29” and “C01-46”
terminals of ECM connector.
It resistance below 12
Ω?HO2S-1 heater circuit is
OK.
Substitute a known-
good ECM and recheck.“BLK/WHT”, “BLK/RED”
and / or “BLK” wire is
high resistance circuit. Step Action Yes No

Downloaded from www.Manualslib.com manuals search engine 1A-62 Engine General Information and Diagnosis:
2HO2S-2 heater power circuit check
1) Disconnect connector from HO2S-2 with ignition switch
turned OFF.
2) Check for proper connection to HO2S-2 at “BLK/WHT”
and “RED/BLU” wire terminals.
3) If wire and connection are OK, measure voltage
between “BLK/WHT” wire terminal of HO2S-2 connector
and engine ground with ignition switch turned ON.
Is voltage over 10 V?Go to Step 3. “BLK/WHT” wire is open
circuit or shorted to
ground circuit.
3HO2S-2 heater power circuit check
1) Disconnect connectors from ECM with ignition switch
turned OFF.
2) Measure resistance between “BLK/WHT” wire terminal
of HO2S-2 connector and “E01-29” terminal wire of ECM
connector.
Is resistance below 5
Ω?Go to Step 4. “BLK/WHT” wire is high
resistance circuit.
4HO2S-2 heater drive circuit check
1) Measure resistance between “RED/BLU” wire terminal of
HO2S-2 connector and vehicle body ground.
Is resistance infinity?Go to Step 5. “RED/BLU” wire is
shorted to ground
circuit.
5HO2S-2 heater drive circuit check
1) Turn ON ignition switch.
2) Measure voltage between “RED/BLU” wire terminal of
HO2S-2 connector and vehicle body ground.
Is voltage 0 V?Go to Step 6. “RED/BLU” wire is
shorted to power circuit.
6HO2S-2 heater drive circuit check
1) Connect connector to HO2S-2 with ignition switch turned
OFF.
2) Turn ON ignition switch.
3) Measure voltage between “C01-47” terminal of
disconnected ECM connector and vehicle body ground.
Is voltage over 10 V?Go to Step 7. “RED/BLU” wire is open
circuit.
7HO2S-2 heater check
1) Disconnect HO2S-2 connector with ignition switch
turned OFF.
2) Check HO2S-2 heater resistance referring to “Heated
Oxygen Sensor (HO2S-1 and HO2S-2) Heater On-
Vehicle Inspection (If Equipped) in Section 1C”.
Is resistance within specified value?Go to Step 8. Replace HO2S-2.
8HO2S-2 heater power circuit check
1) Connect connector to HO2S-2 with ignition switch turned
OFF.
2) Measure resistance between “E01-29” and “C01-47”
terminals of ECM connector.
Is resistance below 30
Ω?HO2S-2 heater circuit is
OK. Substitute a known-
good ECM and recheck.“RED/BLU” wire is high
resistance circuit. Step Action Yes No

Downloaded from www.Manualslib.com manuals search engine 1A-94 Engine General Information and Diagnosis:
4HO2S-1 ground check
1) Disconnect connector from HO2S-1 with ignition switch
turned OFF.
2) Check for proper connection to HO2S-1 connector at
“BLK/RED”, “WHT”, “BLK/WHT” and “ORN” wire
terminals.
3) If connections are OK, measure resistance between
“ORN” wire terminal of HO2S-1 connector and engine
ground.
Is measured resistance less than 5
Ω?Go to Step 5. “ORN” wire is open or
high resistance circuit.
Poor “C01-57” terminal
connection. Faulty ECM
ground.
If they are OK,
substitute a known-
good ECM and recheck.
5Wire circuit check
1) Turn OFF ignition switch.
2) Remove ECM from its bracket with ECM connectors
connected.
3) Measure resistance between “WHT” wire terminal of
HO2S-1 connector and “C01-10” terminal of ECM
connector.
Is resistance less than 5
Ω?Go to Step 6. “WHT” wire is high
resistance circuit or
open circuit. Poor “C01-
10” terminal connection.
Faulty ECM ground. If
they are OK, substitute
a known-good ECM and
recheck.
6Wire circuit check
1) Disconnect connectors from ECM with ignition switch
turn OFF.
2) Measure resistance between “WHT” wire terminal of
HO2S-1 connector and vehicle body ground.
Is resistance infinity?Go to Step 7. “WHT” wire is shorted to
ground circuit.
7HO2S-1 signal circuit check
1) Measure voltage between “WHT” wire terminal of HO2S-
1 connector and vehicle body ground.
Is voltage 0 V?Go to Step 8. “WHT” wire is shorted to
other circuit.
8HO2S-1 heater circuit check
1) Check HO2S-1 heater circuit referring to “DTC P0031 /
P0032: HO2S Heater Control Circuit Low / High
(Sensor-1)”.
Is circuit in good condition?Go to Step 9. Repair HO2S-1 circuit.
9Exhaust system check
1) Check exhaust system for exhaust gas leakage.
Is it OK?Go to Step 4 in “DTC
P0171 / P0172: Fuel
System Too Lean /
Rich”.
If it is in good condition,
go to Step 10.Repair leakage of
exhaust system.
10Air intake system check
1) Check air intake system for clog or leak.
Is it OK?Replace HO2S-1
referring to “Heated
Oxygen Sensor (HO2S-
1 and HO2S-2)
Removal and
Installation (If Equipped)
in Section 1C”.
If DTC still exists,
substitute a known-
good ECM and recheck.Repair or replace air
intake system. Step Action Yes No

Downloaded from www.Manualslib.com manuals search engine Engine General Information and Diagnosis: 1A-95
DTC P0133: O2 Sensor (HO2S) Circuit Slow Response (Sensor-1)S6RW0D1104032
Wiring Diagram
Refer to “DTC P0131 / P0132: O2 Sensor (HO2S) Circuit Low Voltage / High Voltage (Sensor-1)”.
DTC Detecting Condition and Trouble Area
DTC Confirmation Procedure
WARNING!
• When performing a road test, select a place where there is no traffic or possibility of a traffic
accident and be very careful during testing to avoid occurrence of an accident.
• Road test should be carried out by 2 persons, a driver and a tester, on a level road.

NOTE
Check to make sure that following conditions are satisfied when using this “DTC Confirmation
Procedure”.
• Intake air temperature at engine start: –10 °C (14 °F) to 80 °C (176 °F)
• Intake air temperature: –10 °C (14 °F) to 70 °C (158 °F)
• Engine coolant temperature: 70 °C (158 °F) or more
• Altitude (barometric pressure): 2500 m, 8200 ft or less (560 mmHg, 74.4 kPa or more)

1) With ignition switch turned OFF, connect scan tool.
2) Turn ON ignition switch and clear DTC using scan tool.
3) Start engine and warm up to normal operating temperature.
4) Drive vehicle at 40 mph (60 km/h) or higher. (engine speed: 2500 – 3000 r/min.)
5) Keep above vehicle speed for 6 min. or more. (Throttle valve opening is kept constant in this step.)
6) Release accelerator pedal and with engine brake applied, keep vehicle coasting (with fuel cut for 3 sec. or more)
and then stop vehicle.
7) For european market model, check whether O2 sensor readiness/monitoring test has completed or not by using
scan tool.
If O2 sensor readiness/monitoring test has not completed, check vehicle conditions (environmental) and repeat
Step 3) through 6).
8) Check DTC and pending DTC.
DTC Troubleshooting
NOTE
Before this troubleshooting is performed, read the precautions for DTC troubleshooting referring to
“Precautions for DTC Troubleshooting”.

DTC detecting condition Trouble area
Response time (time to change from lean to rich or from rich to lean) of HO2S-1 output
voltage is about 1 sec. at minimum or average time of 1 cycle is 5 sec. at minimum.
(2 driving cycle detection logic, monitoring once / 1 driving)Heated oxygen sensor-1
Step Action Yes No
1Was “Engine and Emission Control System Check”
performed?Go to Step 2. Go to “Engine and
Emission Control
System Check”.
2Is there DTC(s) other than HO2S-1 (DTC P0133)?Go to applicable DTC
diag. flow.Replace HO2S-1.

Downloaded from www.Manualslib.com manuals search engine 1A-98 Engine General Information and Diagnosis:
DTC P0137 / P0138: O2 Sensor (HO2S) Circuit Low Voltage / High Voltage (Sensor-2)S6RW0D1104034
Wiring Diagram
DTC Detecting Condition and Trouble Area8Air intake system check
1) Check air intake system for clog or leak.
Is it OK?Replace HO2S-1
referring to “Heated
Oxygen Sensor (HO2S-
1 and HO2S-2)
Removal and
Installation (If Equipped)
in Section 1C”.
If DTC still exists,
substitute a known-
good ECM and recheck.Repair or replace air
intake system. Step Action Yes No
E01C01
3 4
18 19 5 6 7 10 11
17 20
47 46 49 50 51 21 22
5216 259
24 14
29
55 57 54 53 59
60 582
26 27 28 15
30
56 4832 31 34 35 36 37 40 42 39 38 44
45 43 41 331 12 13
238 3 4
18 19 5 6 7 10 11
17 20
47 46 49 50 51 21 22
5216 259
24 14
29
55 57 54 53 59
60 582
26 27 28 15
30
56 4832 31 34 35 36 37 40 42 39 38 44
45 43 41 331 12 13
238
BLK/WHT
WHT
11
GRN
39
E01-29
BRN
ORN
BLK/WHT
BLKC01-47
C01-11
C01-57
6
2 7
10
BLK
BLUWHT
RED/BLU
1
4
5
8
12
5V
I6RW0D110028-01
1. Main fuse box 4. Junction block assembly 7. Heater 10. To HO2S-1
2. Shield wire 5. “IG COIL” fuse 8. To HO2S-1 heater 11. Individual circuit fuse box No.1
3. Ignition switch 6. HO2S-2 9. ECM 12. “IG ACC” fuse
DTC detecting condition Trouble area
DTC P0137:
HO2S-2 voltage is lower than specified value while engine is idling after driving with
high engine load (high speed) for specified time. And HO2S-2 max. voltage minus
HO2S-2 min. voltage is less than specified value for 40 sec.
(2 driving cycle detection logic)
DTC P0138:
HO2S-2 voltage is higher than specified value while engine is idling after driving with
high engine load (high speed) for specified time. And HO2S-2 max. voltage minus
HO2S-2 min. voltage is less than specified value for 40 sec.
(2 driving cycle detection logic)•HO2S-2
• HO2S-2 circuit
• Fuel system
•ECM
• Fuel shortage
• Exhaust system
• Air intake system

Downloaded from www.Manualslib.com manuals search engine 1A-100 Engine General Information and Diagnosis:
4HO2S-2 ground check
1) Disconnect connector from HO2S-2 with ignition switch
turned OFF.
2) Check for proper connection to HO2S-2 connector at
“RED/BLU”, “BRN”, “ORN” and “BLK/WHT” wire
terminals.
3) If connections are OK, measure resistance between
“ORN” wire terminal of HO2S-2 connector and engine
ground.
Is resistance less than 5
Ω?Go to Step 5. “ORN” wire is open or
high resistance circuit.
Poor “C01-57” terminal
connection. Faulty ECM
ground.
If they are OK,
substitute a known-
good ECM and recheck.
5Wire circuit check
1) Turn OFF ignition switch.
2) Remove ECM from its bracket with ECM connectors
connected.
3) Measure resistance between “BRN” wire terminal of
HO2S-2 connector and “C01-11” terminal of ECM
connector.
Is resistance less than 5
Ω?Go to Step 6. “BRN” wire is high
resistance circuit or
open circuit. Poor “C01-
11” terminal connection.
If they are OK,
substitute a known-
good ECM and recheck.
6Wire circuit check
1) Disconnect connectors from ECM with ignition switch
turned OFF.
2) Measure resistance between “BRN” wire terminal of
HO2S-2 connector and vehicle body ground.
Is resistance infinity?Go to Step 7. “BRN” wire is shorted to
ground circuit.
7HO2S-2 signal circuit check
1) Measure voltage between “BRN” wire terminal of HO2S-
2 connector and vehicle body ground.
Is voltage 0 V?Go to Step 8. “BRN” wire is shorted to
other circuit.
8HO2S-2 heater circuit check
1) Check HO2S-2 heater circuit referring to “DTC P0037 /
P0038: HO2S Heater Control Circuit Low / High
(Sensor-2)”.
Is circuit in good condition?Go to Step 9. Repair HO2S-2 circuit.
9Exhaust system check
1) Check exhaust system for exhaust gas leakage.
Is it OK?Go to Step 4 in “DTC
P0171 / P0172: Fuel
System Too Lean /
Rich”.
If it is in good condition,
go to Step 10.Repair leakage of
exhaust system.
10Air intake system check
1) Check air intake system for clog or leak.
Is it OK?Replace HO2S-2
referring to “Heated
Oxygen Sensor (HO2S-
1 and HO2S-2)
Removal and
Installation (If Equipped)
in Section 1C”.
Is DTC still exists,
substitute a known-
good ECM and recheck.Repair or replace air
intake system. Step Action Yes No

Downloaded from www.Manualslib.com manuals search engine 1A-102 Engine General Information and Diagnosis:
3Wire circuit check
1) Turn OFF ignition switch.
2) Remove ECM from its bracket with ECM connectors
connected.
3) Measure resistance between “BRN” wire terminal of
HO2S-2 connector and “C01-11” terminal of ECM
connector.
Is resistance less than 5
Ω?Go to Step 4. “BRN” wire is high
resistance circuit or
open circuit. Poor “C01-
11” terminal connection.
If they are OK,
substitute a known-
good ECM and recheck.
4HO2S-2 signal circuit check
1) Disconnect connectors from ECM with ignition switch
turned OFF.
2) Measure voltage between “BRN” wire terminal of HO2S-
2 connector and vehicle body ground.
Is voltage 0 V?Go to Step 5. “BRN” wire is shorted to
other circuit.
5HO2S-2 heater circuit check
1) Check HO2S-2 heater circuit referring to “DTC P0037 /
P0038: HO2S Heater Control Circuit Low / High
(Sensor-2)”.
Is circuit in good condition?Go to Step 6. Repair HO2S-2 circuit. If
circuit is OK, substitute
a known-good ECM and
recheck.
6Exhaust system check
1) Check exhaust system for exhaust gas leakage.
Is it OK?Go to Step 4 in “DTC
P0171 / P0172: Fuel
System Too Lean /
Rich”.
If it is in good condition,
go to Step 8.Repair leakage of
exhaust system.
7Air intake system check
1) Check air intake system for clog or leak.
Is it OK?Replace HO2S-2
referring to “Heated
Oxygen Sensor (HO2S-
1 and HO2S-2)
Removal and
Installation (If Equipped)
in Section 1C”.
If DTC still exists,
substitute a known-
good ECM and recheck.Repair or replace air
intake system. Step Action Yes No

Downloaded from www.Manualslib.com manuals search engine Engine General Information and Diagnosis: 1A-103
DTC P0171 / P0172: Fuel System Too Lean / RichS6RW0D1104036
DTC Detecting Condition and Trouble Area
DTC Confirmation Procedure
WARNING!
• When performing a road test, select a place where there is no traffic or possibility of a traffic
accident and be very careful during testing to avoid occurrence of an accident.
• Road test should be carried out by 2 persons, a driver and a tester, on a level road.

NOTE
Check to make sure that following conditions are satisfied when using this “DTC Confirmation
Procedure”.
• Intake air temperature at engine start: –10 °C (14 °F) to 80 °C (176 °F)
• Intake air temperature: –10 °C (14 °F) to 70 °C (158 °F)
• Engine coolant temperature: 70 °C (158 °F) or more
• Altitude (barometric pressure): 2500 m, 8200 ft or less (560 mmHg, 74.4 kPa or more)

1) With ignition switch turned OFF, connect scan tool.
2) Turn ON ignition switch and print Freeze Frame Data or write them down using scan tool.
3) Clear DTC using scan tool.
4) Start engine and warm up to normal operating temperature.
5) Operate vehicle with condition as noted freeze frame data for 5 min.
6) Stop vehicle and check DTC and pending DTC.DTC detecting condition Trouble area
DTC P0171:
Total fuel trim is higher than specified value or short term fuel trim is higher
than specified value for more than 1 min.
(2 driving cycle detection logic)
DTC P0172:
Total fuel trim is lower than specified value or short term fuel trim is lower
than specified value for more than 1 min.
(2 driving cycle detection logic)• Vacuum leakage
• Exhaust gas leakage
• Fuel pressure out of specification
• Fuel injector malfunction
• Heated oxygen sensor-1 malfunction
• MAF sensor malfunction
• ECT sensor malfunction

Downloaded from www.Manualslib.com manuals search engine 1A-124 Engine General Information and Diagnosis:
DTC P0420: Catalyst System Efficiency below ThresholdS6RW0D1104045
System and Wiring Diagram
Circuit Description
ECM monitors oxygen concentration in the exhaust gas which has passed the warm up three way catalytic converter
by HO2S-2. When the catalyst is functioning properly, the variation cycle of HO2S-2 output voltage (oxygen
concentration) is slower than that of HO2S-1 output voltage because of the amount of oxygen in the exhaust gas
which has been stored in warm up three way catalytic converter.
DTC Detecting Condition and Trouble Area
C01-11
C01-10
C01-57
WHT
BRN
1
32
4
5 VORNORN
BLUWHTBLUWHT5
E01C01
3 4
18 19 5 6 7 10 11
17 20
47 46 49 50 51 21 22
5216 259
24 14
29
55 57 54 53 59
60 582
26 27 28 15
30
56 4832 31 34 35 36 37 40 42 39 38 44
45 43 41 331 12 13
238 3 4
18 19 5 6 7 10 11
17 20
47 46 49 50 51 21 22
5216 259
24 14
29
55 57 54 53 59
60 582
26 27 28 15
30
56 4832 31 34 35 36 37 40 42 39 38 44
45 43 41 331 12 13
238
I6RW0D110038-01
1. HO2S-1 3. Warm up three way catalytic converter 5. ECM
2. HO2S-2 4. Three way catalytic converter
DTC detecting condition Trouble area
• While vehicle running at constant speed under other than high load.
• Time from rich or lean switching command is output till HO2S-2
output voltage crosses 0.45 V is less than specified value.
(2 driving cycle detection logic, monitoring once / 1 driving)• Exhaust gas leak
• Warm up three way catalytic converter
malfunction
• HO2S-2 malfunction
• HO2S-1 malfunction