B -- REPLACE EXHAUST MANIFOLD SUB-ASSEMBLY LH (TWC: FRONT CATALYST)
A -- Continue to next step.
5. REPLACE EXHAUST MANIFOLD SUB-ASSEMBLY RH (TWC: FRONT CATALYST)
(a) Replace the exhaust manifold sub-assembly RH (TWC: Front catalyst) See: Engine, Cooling and Exhaust/Exhaust System/Exhaust
Manifold/Service and Repair/Components.
NEXT -- REPLACE CENTER EXHAUST PIPE ASSEMBLY (TWC: REAR CATALYST)
6. REPLACE EXHAUST MANIFOLD SUB-ASSEMBLY LH (TWC: FRONT CATALYST)
(a) Replace the exhaust manifold sub-assembly LH (TWC: Front catalyst) See: Engine, Cooling and Exhaust/Exhaust System/Exhaust
Manifold/Service and Repair/Components.
NEXT -- REPLACE CENTER EXHAUST PIPE ASSEMBLY (TWC: REAR CATALYST)
7. INSPECT FOR EXHAUST GAS LEAK
(a) Inspect for exhaust gas leaks from the exhaust manifold sub-assembly and exhaust pipes.
OK:
No gas leaks.
NG -- REPAIR OR REPLACE EXHAUST GAS LEAK POINT
OK -- REPLACE HEATED OXYGEN SENSOR See: Powertrain Management/Computers and Control Systems/Oxygen
Sensor/Service and Repair/Heated Oxygen Sensor/Removal
8. INSPECT FOR EXHAUST GAS LEAK
(a) Inspect for exhaust gas leaks from the exhaust manifold sub-assembly and exhaust pipes.
OK:
No gas leaks.
NG -- REPAIR OR REPLACE EXHAUST GAS LEAK POINT
OK -- CHECK ENGINE TO DETERMINE CAUSE OF EXTREMELY RICH OR LEARN ACTUAL AIR FUEL RATIO
From 08/2009
2GR-FE ENGINE CONTROL: SFI SYSTEM: P0420,P0430: Catalyst System Efficiency Below Threshold (Bank 1)
P0430 - Catalyst System Efficiency Below Threshold (Bank 2)
DESCRIPTION
The ECM uses the sensors mounted in front of and behind the three-way catalytic converter to monitor its efficiency.
The first sensor, the air fuel ratio sensor, sends pre-catalyst information to the ECM. The second sensor, the heated oxygen sensor, sends
post-catalyst information to the ECM.
In order to detect any deterioration in the three-way catalytic converter, the ECM calculates the oxygen storage capacity of the three-way catalytic
converter. This calculation is based on the voltage output of the heated oxygen sensor while performing active air fuel ratio control, rather than the
conventional detecting method, which uses the locus ratio.
The oxygen storage capacity value is an indication of the oxygen storage capacity of the three-way catalytic converter. When the vehicle is being
driven with a warm engine, active air fuel ratio control is performed for approximately 15 to 20 seconds. When it is performed, the ECM deliberately
sets the air fuel ratio to lean or rich levels. If the rich-lean cycle of the heated oxygen sensor is long, the oxygen storage capacity is large. There is a
direct correlation between the oxygen storage capacity of the three-way catalytic converter and the response of the heated oxygen sensor.
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