oxygen sensors TOYOTA CAMRY 2000 Service Owner's Manual

DI±248
± DIAGNOSTICSENGINE (1MZ±FE)
483 Author: Date:
9 Check gas leakage on exhaust system.
NG Repair or replace.
OK
Replace heated oxygen sensors
(bank 1, 2 sensor 1).
10 Perform confirmation driving pattern (See page DI±255).
Go
11 Is there DTC P0125 being output again ?
YES Check and replace ECM
(See page IN±31).
NO
12 Did vehicle runs out of fuel in the past ?
NO Check for intermittent problems
(See page DI±197).
NO
DTC P0125 is caused by running out of fuel.

A00477
CoverAtmosphere
Platinum
Electrode
Solid Electrolyte
(Zirconia Element)
Platinum
Electrode
Heater
Coating (Ceramic)
Exhaust Gas
(V)
4.0
3.8
3.6
3.4
3.2
3.0
2.8
2.6
17
Air±Fuel Ratio
2.4
16 15 12 1413 1918ECM Monitored
A/F Sensor Voltage
± DIAGNOSTICSENGINE (1MZ±FE)
DI±249
484 Author: Date:
DTC P0125 Insufficient Coolant Temp. for Closed Loop
Fuel Control (Only for California Spec.)
CIRCUIT DESCRIPTION
To obtain a high purification rate for the CO, HC and NOx components of the exhaust gas, a three±way
catalytic converter is used, but for the most efficient use of the three±way catalytic converter, the air±fuel
ratio must be precisely controlled so that it is always close to the stoichiometric air±fuel ratio.
The A/F sensor has the characteristic that provides output voltage
* approximately proportional to the existing
air±fuel ratio. The A/F sensor output voltage
* is used to provide feedback for the ECM to control the air±fuel
ratio.
By the A/F sensor output, the ECM can determine the deviation amount from the stoichiometric air±fuel ratio
and control the proper injection time immediately. If the A/F sensor is malfunctioning, ECM is unable to per-
form accurate air±fuel ratio control.
The A/F sensor is equipped with a heater which heats the zirconia element. The heater is controlled by the
ECM. When the intake air volume is low (the temp. of the exhaust gas is low), current flows to the heater
to heat the sensor for accurate oxygen concentration detection.
*: The voltage value changes at the inside of the ECM only.
DTC No.DTC Detecting ConditionTrouble Area
P0125
After engine is warmed up, A/F sensor output* does not
change when conditions (a), (b) and (c) continue for at least
1.5 min.
*: Output value changes at inside of ECM only.
(a) Engine speed: 1,500 rpm or more
(b) Vehicle speed: 40 ~ 100 km/h (25 ~ 62 mph)
(c) Throttle valve does not fully closed
(d) After starting engine
140 sec
Fuel system

Injector

Ignition system

Gas leakage on exhaust system

Open or short in A/F sensor circuit (bank 1, 2 sensor 1)

A/F sensors (bank 1, 2 sensor 1)

ECM
DI07M±09

A07445
B
BB B
2 142
31 23
4
BR
23
1
B±W P±BB B±WB±R
*
1L
E8 E8 E10 E10
E78 9 84 213 122011
AFR+
AFR±
AFL+
AFL± HAFR
OXS
HTS
MREL HAFLECM
3.3 V
3.3 V 3.0 V
3.0 V
E1
B+ E10 E10E10E10 1
J27
Engine Room J/B
F6
F4 2J
2A
2C2K
2
7
5 1
EFI Relay
1
1B
B±W
B±W
B EFI
1 2
2
52
22 3
L W±B1
1 2
A/F HTR
1
W
FL
MAIN FLEngine RoomBattery*
1B±W B
B
B±G
1
2 3
5
E04
E05
E03
*1B±R *1BR *G
*G
*B±W*L
ES1
J27 B
E
Junction
connector
A/F Sensor
(Bank 2, Sensor 1)
B±Y
A/F Sensor
(Bank 1, Sensor 2)
BRII1A
ABR
J22
Junction
Connector J24
Junction
Connector
B±Y
W±B
B±W
J35
J35J36A C
C
EB EC
A/F Sensor
(Bank 1, Sensor 1)
Engine Room
A/F HTR Relay
*: TMC Made
*: TMMK Made
Junction
Connector
4
to Analog±Digital
Converter
to Analog±Digital
Converter
DI±250
± DIAGNOSTICSENGINE (1MZ±FE)
485 Author: Date:
HINT:

After confirming DTC P0125, use the OBD II scan tool or TOYOTA hand-held tester to confirm voltage
output of heated oxygen sensors (bank 1, 2 sensor 1) from CURRENT DATA.

The ECM controls the voltage of AFR, AFL, AFR and AFL terminals of ECM to the fixed volt-
age. Therefore, it is impossible to confirm the A/F sensor output voltage without OBD II scan tool or
TOYOTA hand±held tester.

OBD II scan tool (excluding TOYOTA hand±held tester) displays the one fifth of the A/F sensor output
voltage which is displayed on the TOYOTA hand±held tester.
WIRING DIAGRAM

P18349
DI±256
± DIAGNOSTICSENGINE (1MZ±FE)
491 Author: Date:
HINT:
If a malfunction exists, the MIL will light up during step (6).
NOTICE:
If the conditions in this test are not strictly followed, detection of the malfunction will not be possible.
If you do not have a TOYOTA hand±held tester, turn the ignition switch OFF after performing steps
(3) to (6), then perform steps (3) to (6) again.
INSPECTION PROCEDURE
HINT:
Read freeze frame data using TOYOTA hand±held tester or OBD II scan tool. Because freeze frame records
the engine conditions when the malfunction is detected, when troubleshooting it is useful for determining
whether the vehicle was running or stopped, the engine warmed up or not, the air±fuel ratio lean or rich, etc.
at the time of the malfunction.
1 Are there any other codes (besides DTC P0130, P0150) being output ?
YES Go to relevant DTC chart.
NO
2 Check the output voltage of heated oxygen sensors (bank1, 2 sensor1)
during idling.
PREPARATION:
Warm up the heated oxygen sensors (bank1, 2 sensor1) with the engine at 2,500 rpm for approx. 90 sec.
CHECK:
Use the OBD II scan tool or TOYOTA hand±held tester to read the output voltage of the heated oxygen sen-
sors (bank1, 2 sensor1) during idling.
OK:
Heated oxygen sensors (bank1, 2 sensor1) output voltage:
Alternates repeatedly between less than 0.4 V and more than 0.55 V (See the following table).
OK Go to step 8.
NG

± DIAGNOSTICSENGINE (1MZ±FE)
DI±257
492 Author: Date:
3 Check for open and short in harness and connector between ECM and heated
oxygen sensors (bank1, 2 sensor1) (See page IN±31).
NG Repair or replace harness or connector.
OK
4 Check air induction system (See page SF±1).
NG Repair or replace.
OK
5 Check EGR system (See page EC±11).
NG Replace EGR system.
OK
6 Check fuel pressure (See page SF±6).
NG Check and repair fuel pump, fuel pipe line and
filter (See page SF±1).
OK

DI±258
± DIAGNOSTICSENGINE (1MZ±FE)
493 Author: Date:
7 Check injector injection (See page SF±25).
NG Replace injector.
OK
Replace heated oxygen sensors
(bank1, 2 sensor1).
8 Perform confirmation driving pattern.
Go
9 Are there DTC P0130 and/or P0150 being output again ?
NO Check for intermittent problems
(see page DI±197).
YES
Check and replace ECM
(See page IN±31).

P18349
DI±260
± DIAGNOSTICSENGINE (1MZ±FE)
495 Author: Date:
2 Check the output voltage of heated oxygen sensors (bank1, 2 sensor1)
during idling.
PREPARATION:
Warm up the heated oxygen sensors (bank1, 2 sensor1) with the engine at 2,500 rpm for approx. 90 sec.
CHECK:
Use the OBD II scan tool or TOYOTA hand±held tester to read the output voltage of the heated oxygen sen-
sors (bank1, 2 sensor1) during idling.
OK:
Heated oxygen sensors (bank1, 2 sensor1) output voltage:
Alternates repeatedly between less than 0.4 V and more than 0.55 V (See the following table).
OK Go to step 8.
NG
3 Check for open and short in harness and connector between ECM and heated
oxygen sensors (bank1, 2 sensor1) (See page IN±31).
NG Repair or replace harness or connector.
OK
4 Check air induction system (See page SF±1).
NG Repair or replace.
OK

± DIAGNOSTICSENGINE (1MZ±FE)
DI±261
496 Author: Date:
5 Check EGR system (See page EC±11).
NG Replace EGR system.
OK
6 Check fuel pressure (See page SF±1).
NG Check and repair fuel pump, fuel pipe line and
filter (See page SF±1).
OK
7 Check injector injection (See page SF±25).
NG Replace injector.
OK
Replace heated oxygen sensors
(bank1, 2 sensor1).
8 Perform confirmation driving pattern (See page DI±255).
Go

DI±272
± DIAGNOSTICSENGINE (1MZ±FE)
507 Author: Date:
DTC P0171 System too Lean (Fuel Trim)
(Except California Spec.)
DTC P0172 System too Rich (Fuel Trim)
(Except California Spec.)
CIRCUIT DESCRIPTION
Fuel trim refers to the feedback compensation value compared against the basic injection time. Fuel trim
includes short±term fuel trim and long±term fuel trim.
Short±term fuel trim is the short±term fuel compensation used to maintain the air±fuel ratio at its ideal
theoretical value. The signal from the heated oxygen sensor indicates whether the air±fuel ratio is RICH or
LEAN compared to the ideal theoretical value, triggering a reduction in fuel volume if the air±fuel ratio is rich,
and an increase in fuel volume if it is lean.
Long±term fuel trim is overall fuel compensation carried out long±term to compensate for continual deviation
of the short±term fuel trim from the central value due to individual engine differences, wear over time and
changes in the usage environment.
If both the short±term fuel trim and long±term fuel trim are LEAN or RICH beyond a certain value, it is
detected as a malfunction and the MIL lights up.
DTC No.DTC Detecting ConditionTrouble Area
P0171
When air fuel ratio feedback is stable after engine warming up,
fuel trim is considerably in error on RICH side
(2 trip detection logic)

Air intake (hose loose)

Fuel line pressure

Injector blockage

Heated oxygen sensors (bank 1, 2 sensor 1) malfunction

Mass air flow meter

Engine coolant temp. sensor

Gas leakage on exhaust system
P0172
When air fuel ratio feedback is stable after engine warming up,
fuel trim is considerably in error on LEAN side
(2 trip detection logic)

Fuel line pressure

Injector leak, blockage

Heated oxygen sensors (bank 1, 2 sensor 1) malfunction

Mass air flow meter

Engine coolant temp. sensor

Gas leakage on exhaust system
HINT:

When DTC P0171 is recorded, the actual air±fuel ratio is on the LEAN side. When DTC P0172 is re-
corded, the actual air±fuel ratio is on the RICH side.

If the vehicle runs out of fuel, the air±fuel ratio is LEAN and DTC P0171 is recorded. The MIL then
comes on.

If the total of the short±term fuel trim value and long±term fuel trim value is within + 35 % (80°C (176°F)
or more), the system is functioning normally.
INSPECTION PROCEDURE
HINT:
Read freeze frame data using TOYOTA hand±held tester or OBD II scan tool. Because freeze frame records
the engine conditions when the malfunction is detected, when troubleshooting it is useful for determining
whether the vehicle was running or stopped, the engine warmed up or not, the air±fuel ratio lean or rich, etc.
at the time of the malfunction.
DI4DR±01

P18349
DI±274
± DIAGNOSTICSENGINE (1MZ±FE)
509 Author: Date:
6 Check gas leakage on exhaust system.
NG Repair or replace.
OK
7 Check the output voltage of heated oxygen sensors (bank1, 2 sensor1) during
idling.
PREPARATION:
Warm up the heated oxygen sensors (bank1, 2 sensor1) the engine at 2,500 rpm for approx. 90 sec.
CHECK:
Use the OBDII scan tool or TOYOTA hand±held tester to read the output voltage of the heated oxygen sen-
sors (bank1, 2 sensor1) during idling.
OK:
Heated oxygen sensors (bank1, 2 sensor1) output voltage:
Alternates repeatedly between less than 0.4 V and more than 0.55 V (See the Following table).
OK Go to step 9.
NG