1999 TOYOTA CAMRY coolant temp sensors
[x] Cancel search: coolant temp sensorsPage 1273 of 4592
P21242 FI7210
A00027
Atmosphere
Flange
Platinum Electrode
Solid Electrolyte
(Zirconia Element)
Platinum Electrode
Heater
Coating (Ceramic)
Exhaust GasCoverIdeal Air±Fuel Mixture
Output Voltage
Richer ± Air Fuel Ratio ± Leaner
± DIAGNOSTICSENGINE (5S±FE)
DI±61
296 Author: Date:
DTC P0125 Insufficient Coolant Temp. for Closed Loop
Fuel Control (Except 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 heated oxygen sensor has the characteristic where by its output voltage changes suddenly in the vicinity
of the stoichiometric air±fuel ratio. This is used to detect the oxygen concentration in the exhaust gas and
provide feedback to the computer for control of the air±fuel ratio.
When the air±fuel ratio becomes LEAN, the oxygen concentration in the exhaust increases and the heated
oxygen sensor informs the ECM of the LEAN condition (small electromotive force: 0 V).
When the air±fuel ratio is RICHER than the stoichiometric air±fuel ratio the oxygen concentration in the ex-
haust gas is reduced and the heated oxygen sensor informs the ECM of the RICH condition (large electromo-
tive force: 1 V).
The ECM judges by the electromotive force from the heated oxygen sensor whether the air±fuel ratio is RICH
or LEAN and controls the injection time accordingly. However, if malfunction of the heated oxygen sensor
causes output of abnormal electromotive force, the ECM is unable to perform accurate air±fuel ratio control.
The heated oxygen sensors include a heater which heats the zirconia element. The heater is controlled by
the ECM. When the intake air volume is low (the temperature of the exhaust gas is low) current flows to the
heater to heat the sensor for accurate oxygen concentration detection.
DTC No.DTC Detecting ConditionTrouble Area
P0125
After engine is warmed up, heated oxygen sensor (bank 1
sensor 1) output does not indicate RICH even once when
conditions (a), (b) and (c) continue for at least 1.5 min.:
(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
Fuel system
Injector
Ignition system
Gas leakage on exhaust system
Open or short in heated oxygen sensor (bank 1 sensor 1)
circuit
Heated oxygen sensor (bank 1 sensor 1)
ECM
DI00T±05
Page 1456 of 4592
P21242 FI7210
A00027
Atmosphere
CoverIdeal Air±Fuel Mixture
Air Fuel Ratio
RicherLeaner
Exhaust GasFlange
Platinum Electrode
Solid Electrolyte
(Zirconia Element)
Platium Electrode
Heater
Coating(Ceramic)
Output Voltage
DI±244
± DIAGNOSTICSENGINE (1MZ±FE)
479 Author: Date:
DTC P0125 Insufficient Coolant Temp. for Closed Loop
Fuel Control (Except 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 oxygen sensor has the characteristic whereby its output voltage changes suddenly in the vicinity of the
stoichiometric air±fuel ratio. This characteristic is used to detect the oxygen concentration in the exhaust
gas and provide feedback to the computer for control of the air±fuel ratio.
When the air±fuel ratio becomes LEAN, the oxygen concentration in the exhaust increases and the oxygen
sensor informs the ECM of the LEAN condition (small electromotive force: < 0.45 V).
When the air±fuel ratio is RICHER than the stoichiometric air±fuel ratio the oxygen concentration in the ex-
haust gas is reduced and the oxygen sensor informs the ECM of the RICH condition (large electromotive
force: > 0.45 V). The ECM judges by the electromotive force from the oxygen sensor whether the air±fuel
ratio is RICH or LEAN and controls the injection time accordingly. However, if malfunction of the oxygen sen-
sor causes output of abnormal electromotive force, the ECM is unable to perform accurate air±fuel ratio con-
trol.
The heated oxygen sensors include a heater which heats the zirconia element. The heater is controlled by
the ECM. When the intake air volume is low (the temperature of the exhaust gas is low) current flows to the
heater to heat the sensor for accurate oxygen concentration detection.
DTC No.DTC Detecting ConditionTrouble Area
P0125
After engine is warmed up, heated oxygen sensor (bank 1, 2
sensor 1) output does not indicate RICH ( 0.45 V ) even
once when conditions (a), (b), (c) and (d) continue for at least
2 min.:
(a) Engine speed: 1,500 rpm or more
(b) Vehicle speed: 40 SPD and 100 km/h (25 SPD and
62 mph)
(c) Throttle valve does not fully closed
(d) 140 sec. or more after starting engineFuel system
Injector
Ignition system
Gas leakage on exhaust system
Open or short in heated oxygen sensors (bank 1, 2 sensor 1)
circuit
Heated oxygen sensors (bank 1, 2 sensor 1)
ECM
DI07M±08
Page 1461 of 4592
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 secFuel 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
Page 1479 of 4592
± DIAGNOSTICSENGINE (1MZ±FE)
DI±267
502 Author: Date:
DTC P0171 System too Lean (Fuel Trim)
(Only for California Spec.)
DTC P0172 System too Rich (Fuel Trim)
(Only for 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 A/F sensor is approximately proportional to the existing air±fuel ratio, and ECM compar-
ing it with the ideal theoretical value, the ECM reduces fuel volume immediately if the air±fuel ratio is rich
and increases fuel volume if it is lean.
Long±term fuel trim compensates the deviation from the central value of the short±term fuel trim stored up
by each engine tolerance, and the deviation from the central value due to the passage of time and changes
of using environment.
If both the short±term fuel trim and long±term fuel trim exceed 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)
Gas leakage on exhaust system
Air intake (hose loose)
Fuel line pressure
Injector blockage
Mass air flow meter
Engine coolant temp. sensor
A/F sensors (bank 1, 2 sensor 1)
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)
Gas leakage on exhaust system
Fuel line pressure
Injector leak, blockage
Mass air flow meter
Engine coolant temp. sensor
A/F sensors (bank 1, 2 sensor 1)
DI07R±05
Page 1480 of 4592
DI±268
± DIAGNOSTICSENGINE (1MZ±FE)
503 Author: Date:
HINT:
When the DTC P0171 is recorded, the actual air±fuel ratio is on the lean side. When DTC P0172 is
recorded, 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.
The A/F sensors (bank 1, 2 sensor 1) output voltage and the short±term fuel trim value can be read
using the OBD II scan tool or TOYOTA hand±held tester.
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 sensors (bank
1, 2 sensor 1) output voltage which is displayed on the TOYOTA hand±held tester.
INSPECTION PROCEDURE
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 Check air induction system (See page SF±1).
NG Repair or replace.
OK
2 Check injector injection (See page SF±25).
NG Replace injector.
OK
3 Check mass air flow meter and engine coolant temp. sensor
(See pages SF±35 and SF±63).
NG Repair or replace.
OK
Page 1484 of 4592
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
Page 1557 of 4592
± DIAGNOSTICSENGINE (1MZ±FE)
DI±345
580 Author: Date:
DTC P1133 A/F Sensor Circuit Response Malfunction
(Bank 1 Sensor 1) (Only for California Spec.)
DTC P1153 A/F Sensor Circuit Response Malfunction
(Bank 2 Sensor 1) (Only for California Spec.)
CIRCUIT DESCRIPTION
Refer to DTC P0125 (Insufficient Coolant Temp. for Closed Loop Fuel Control (Only for California Spec.))
on page DI±249.
DTC No.DTC Detecting ConditionTrouble Area
P1133
P1155
After engine is warmed up and during vehicle driving at
engine speed 1,400 rpm or more and vehicle speed 60
km/h (38 mph) or more, if response characteristic of A/F
sensor becomes deteriorated
(2 trip detection logic)
A/F sensors (bank 1, 2 sensor 1)
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 P1133, P1153) being output?
YES Go to relevant DTC chart.
NO
DI1K7±03
Page 1561 of 4592
A02509
HAFL (+)
HAFR (+)
± DIAGNOSTICSENGINE (1MZ±FE)
DI±349
584 Author: Date:
DTC P1135 A/F Sensor Heater Circuit Malfunction
(Bank 1 Sensor 1) (Only for California Spec.)
DTC P1155 A/F Sensor Heater Circuit Malfunction
(Bank 2 Sensor 1) (Only for California Spec.)
CIRCUIT DESCRIPTION
Refer to DTC P0125 (Insufficient Coolant Temp. for Closed Loop Fuel Control (Only for California Spec.))
on page DI±249.
DTC No.DTC Detecting ConditionTrouble Area
P1135
When heater operates, heater current exceeds 8 A
(2 trip detection logic)Open or in heater circuit of A/F sensors
(bank 1, 2 sensor 1)P1135
P1155Heater current of 0.25 A or less when heater operates
(2 trip detection logic)
(bank 1, 2 sensor 1)
A/F sensors (bank 1, 2 sensor 1) heater
ECM
WIRING DIAGRAM
Refer to DTC P0125 (Insufficient Coolant Temp. for Closed Loop Fuel Control (Only for California Spec.))
on page DI±249.
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 Check voltage between terminal HAFR, HAFL of ECM connector and body
ground.
PREPARATION:
(a) Remove glove compartment (See page SF±73).
(b) Turn the ignition switch ON.
CHECK:
Measure voltage between terminals HAFR, HAFL of the ECM
connector and body ground.
OK:
Voltage: 9 ~ 14 V
OK Check and replace ECM (See page IN±31).
NG
DI1K8±04