catalytic converter TOYOTA CAMRY 1999 Service Owner's Manual

A00477
Atmosphere
Cover
Exhaust GasPlatinum
Electrode
Solid Electrolyte
(Zirconia Element)
Platinum
Electrode
Heater
Air±Fuel Ratio
(V)
2.6 4.0
3.8
3.6
3.4
3.2
3.0
2.8
2.4
14 15 16 17 19 21 22
Coating (Ceramic)
ECM Monitored
A/F Sensor Voltage
DI±40
± DIAGNOSTICSENGINE
DTC P0125 Insufficient Coolant Temp. for Closed Loop
Fuel Control
CIRCUIT DESCRIPTION
To obtain a high purification rate for the CO, HC and NOx components of the exhaust gas, a three±way cata-
lytic 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 exist-
ing 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 is not fully closed
Open or short in A/F sensor (bank 1 sensor 1) circuit

A/F sensor (bank 1 sensor 1)

Air induction system

EGR system

Fuel pressure

Injector

Gas leakage on exhaust system

ECM
HINT:

After confirming DTC P0125, use the OBD II scan tool or TOYOTA hand-held tester to confirm voltage
output of A/F sensor from the CURRENT DATA.

The ECM controls the voltage of the AF+ and AF± terminals of the ECM to the fixed voltage. Therefore,
it is impossible to confirm the A/F sensor output voltage without OBD II scan tool or TOYOTA hand±
held tester.
DI1JU±04

EC039±05
± EMISSION CONTROL (5S±FE)EMISSION CONTROL SYSTEM
EC±1
1399 Author: Date:
EMISSION CONTROL SYSTEM
PURPOSE
The emission control systems are installed to reduce the amount of HC, CO and NOx exhausted from the
engine ((3), (4) and (5)), to prevent the atmospheric release of blow±by gas±containing HC (1) and evapo-
rated fuel containing HC being released from the fuel tank (2).
The function of each system is shown in the following table.
SystemAbbreviationFunction
(1) Positive Crankcase Ventilation
(2) Evaporative Emission Control
(3) Exhaust Gas Recirculation
(4) Three±Way Catalytic Converter
(5) Sequential Multiport Fuel Injection*PCV
EVAP
EGR
TWC
SFIReduces HC
Reduces evaporated HC
Reduces NOx
Reduces HC, CO and NOx
Injects a precisely timed, optimum amount of fuel for reduced
exhaust emissions
Remark: * For inspection and repair of the SFI system, refer to the SFI section in this manual.

EC03H±03
± EMISSION CONTROL (5S±FE)THREE±WAY CATALYTIC CONVERTER (TWC)
SYSTEMEC±15
1413 Author: Date:
THREE±WAY CATALYTIC CONVERTER (TWC) SYSTEM
ON±VEHICLE INSPECTION
1. INSPECT EXHAUST PIPE ASSEMBLY
(a) Check the connections for looseness or damage.
(b) Check the clamps for weakness, cracks or damage.
2. INSPECT REAR TWC
Check for dents or damage.
If any part of the protector is damaged or dented to the extent that it contacts the TWC, repair or replace
it.
3. INSPECT REAR TWC HEAT INSULATOR
(a) Check the heat insulator for damage.
(b) Check for adequate clearance between the catalytic converter and heat insulator.

EC03I±04
B06537
Front TWC (California)
Exhaust Manifold
(Front TWC)
No.3 Exhaust
Manifold Heat
Insulator
No.2 Exhaust
Manifold Stay
A/F Sensor
GasketA/F Sensor Connector

Gasket Clampx 6




N´m (kgf´cm, ft´lbf)

Non±reusable part
49 (500, 36)
44 (450, 32)
62 (630,46)
: Specified torque
No.1 Exhaust
Manifold Stay


No.1 Exhaust Manifold
Heat Insulator
No.2 Exhaust Manifold
Heat Insulator
(TMC Made)
(TMMK Made)
EC±16± EMISSION CONTROL (5S±FE)THREE±WAY CATALYTIC CONVERTER (TWC)
SYSTEM
1414 Author: Date:
COMPONENTS

B06538
N´m (kgf´cm, ft´lbf)

Non±reusable part
TWC (Except California)
Rear TWC (California)

Gasket
BracketTWC (Except California)
Rear TWC (California)
Front Exhaust Pipe
Gasket
Stay
62 (630, 46)
56 (570, 41)
: Specified torque





± EMISSION CONTROL (5S±FE)THREE±WAY CATALYTIC CONVERTER (TWC)
SYSTEMEC±17
1415 Author: Date:

EC01U±03
± EMISSION CONTROL (1MZ±FE)EMISSION CONTROL SYSTEM
EC±1
1416 Author: Date:
EMISSION CONTROL SYSTEM
PURPOSE
The emission control systems are installed to reduce the amount of CO, HC and NOx exhausted from the
engine ((3), (4), (5) and (6)), to prevent the atmospheric release of blow±by gas±containing HC (1) and evap-
orated fuel containing HC being released from the fuel tank (2).
The function of each system is shown in these table.
SystemAbbreviationFunction
(1) Positive Crankcase Ventilation
(2) Evaporative Emission Control
(3) Exhaust Gas Recirculation
(4) Warm Up Three±Way Catalytic Converter
(5) Three±Way Catalytic Converter
(6) Sequential Multiport Fuel Injection*PCV
EVAP
EGR
WU±TWC
TWC
SFIReduces HC
Reduces evaporated HC
Reduces NOx
Reduces HC, CO and NOx
Reduces HC, CO and NOx
Injects a precisely timed, optimum amount of fuel for reduced
exhaust emissions
Remark: * For inspection and repair of the SFI system, refer to the SF section of this manual.

EC020±04
EC±14± EMISSION CONTROL (1MZ±FE)WARM UP THREE±WAY CATALYTIC CONVERTER
(WU±TWC) SYSTEM (California A/T)
1429 Author: Date:
WARM UP THREE±WAY CATALYTIC CONVERTER
(WU±TWC) SYSTEM (California A/T)
ON±VEHICLE INSPECTION
1. INSPECT EXHAUST PIPE ASSEMBLY
(a) Check the connections for looseness or damage.
(b) Check the clamps for weakness, cracks or damage.
2. INSPECT WU±TWC
Check for dents or damage.
If any part of the protector is damaged or dented to the extent that it contacts the WU±TWC, repair or replace
it.
3. INSPECT WU±TWC HEAT INSULATOR
(a) Check the heat insulator for damage.
(b) Check for adequate clearance between the catalytic converter and heat insulator.

EC021±04
B06395
N´m (kgf´cm, ft´lbf) : Specified torque

Non±reusable partBracket

Gasket
Stay
62 (630, 46)
33 (330, 24)
56 (570, 41)
WU±TWCFront Exhaust Pipe
(Type A)
Gasket


62 (630, 46)
33 (330, 24)
WU±TWC for Bank 1


21 (210, 15)
Front Exhaust Pipe
WU±TWC
Type B
± EMISSION CONTROL (1MZ±FE)WARM UP THREE±WAY CATALYTIC CONVERTER
(WU±TWC) SYSTEM (California A/T)EC±15
1430 Author: Date:
COMPONENTS

B06478
WU±TWC for Bank 2
LH Exhaust Manifold
(with WU±TWC)
LH Exhaust Manifold
Heat InsulatorA/F Sensor Connector
A/F Sensor
LH Exhaust Manifold Stay
Gasket
Gasket
49 (500, 63)
62 (630, 46)
44 (450, 32)
x 6


N´m (kgf´cm, ft´lbf) : Specified torque

Non±reusable part
EC±16± EMISSION CONTROL (1MZ±FE)WARM UP THREE±WAY CATALYTIC CONVERTER
(WU±TWC) SYSTEM (California A/T)
1431 Author: Date:

EC022±04
± EMISSION CONTROL (1MZ±FE)THREE±WAY CATALYTIC CONVERTER (TWC)
SYSTEMEC±17
1432 Author: Date:
THREE±WAY CATALYTIC CONVERTER (TWC) SYSTEM
ON±VEHICLE INSPECTION
1. INSPECT EXHAUST PIPE ASSEMBLY
(a) Check the connections for looseness or damage.
(b) Check the clamps for weakness, cracks or damage.
2. INSPECT TWC
Check for dents or damage.
If any part of the protector is damaged or dented to the extent that it contacts the TWC, repair or replace
it.
3. INSPECT TWC HEAT INSULATOR
(a) Check the heat insulator for damage.
(b) Check for adequate clearance between the catalytic converter and heat insulator.