Toyota RAV4 manuals

Toyota Sienna Service Manual: Catalyst System Efficiency Below Threshold

DTC P0420 Catalyst System Efficiency Below Threshold (Bank 1)

DTC P0430 Catalyst System Efficiency Below Threshold (Bank 2)

MONITOR DESCRIPTION

The ECM uses the sensors mounted in front of and behind the three-way catalyst (TWC) to monitor its efficiency. The first sensor, an Air Fuel ratio (A/F) sensor, sends pre-catalyst A/F ratio information to the ECM. The second sensor, a heated oxygen sensor (O2S), sends post-catalyst information to the ECM.

The ECM compares these 2 signals to judge the efficiency of the catalyst and the catalyst's ability to store oxygen. During normal operation, the TWC stores and releases oxygen as needed. The capacity to store oxygen results in a low variation in the post-TWC exhaust stream.

If the catalyst is functioning normally, the waveform of the heated oxygen sensor slowly switches between RICH and LEAN. If the catalyst is deteriorated, the waveform will alternate frequently between RICH and LEAN. As the catalyst efficiency degrades, its ability to store oxygen is reduced and the catalyst output becomes more variable. When running the monitor, the ECM compares sensor 1 signals (A/F sensor) over a specific amount of time to determine catalyst efficiency. The ECM begins by calculating the signal length for both sensors (for the rear oxygen sensor, the ECM uses the output voltage signal length). If the oxygen sensor output voltage signal length is greater than the threshold (threshold is calculated based on the A/F sensor signal length), the ECM concludes that the catalyst is malfunctioning. The ECM will turn on the MIL and a DTC will be set.

DTC No.

DTC Detection Condition

Trouble Area

P0420

Oxygen Storage Capacity (OSC) value is smaller than standard value under active air-fuel ratio control (2 trip detection logic)
  • Gas leakage from exhaust system
  • A/F sensor (bank 1 sensor 1)
  • HO2 sensor (bank 1 sensor 2)
  • Exhaust manifold (TWC)

P0430

OSC value is smaller than standard value under active air-fuel ratio control (2 trip detection logic)
  • Gas leakage from exhaust system
  •  A/F sensor (bank 2 sensor 1)
  •  HO2 sensor (bank 2 sensor 2)
  •  Exhaust manifold (TWC)

HINT:

MONITOR STRATEGY

Related DTCs P0420: Catalyst Deterioration
P0430: Catalyst Deterioration
Required Sensors / Components (Main) TWC
Required Sensors / Components (Related) A/F sensor, heated oxygen sensor, intake air temperature sensor, mass air flow meter, crankshaft position sensor and engine coolant temperature sensor
Frequency of Operation Once per driving cycle
Duration Approximately 30 seconds
MIL Operation 2 driving cycles
Sequence of Operation None

TYPICAL ENABLING CONDITIONS

The monitor will run whenever these DTCs are not present P0011, P0012 (VVT System 1-Advance, Retard), P0021, P0022 (VVT System 2- Adavance, Retard), P0031, P0032, P0051, P0052 (A/F Sensor Heater Sensor 1), P0037, P0038, P0057, P0058 (O2 Sensor heater Sensor 2), P0100, P0101, P0102, P0103 (MAF Sensor), P0115, P0116, P0117, P0118 (ECT Sensor), P0120, P0121, P0122, P0123, P0220, P0222, P0223 , P2135 (TP Sensor), P0125 (Insufficient ECT for Closed Loop), P0136, P0156 (O2 Sensor 2), P0171,P0172 (Fuel System), P0300, P0301, P0302, P0303, P0304, P0305, P0306 (Misfire), P0335 (CKP Sensor), P0340 (CMP Sensor), P0351, P0352, P0353, P0354, P0355, P0356 (Ignitor), P0500 (VSS), P2196, P2198 (A/F Sensor (Rationality)), P2A00, P2A03 (A/ F Sensor (Slow Response))
Battery voltage 11 V or more
IAT -10C (14F) or more
ECT 75C (167F) or more
Atmospheric pressure 0.75 or more
Idle OFF
Engine RPM Less than 3200 rpm
A/F sensor Activated
Fuel system status Closed loop
Engine load 10 to 70%
All of the following conditions are met Conditions 1, 2 and 3
1. Mass air flow rate 5 to 60 g/sec
2. Front catalyst temperature (estimated) 600 to 750C (1112 to 1382F)
3. Rear catalyst temperature (estimated) 100 to 900C (212 to 1652F)
Rear HO2S monitor Completed
Shift position 4th or more

TYPICAL MALFUNCTION THRESHOLDS

Oxygen Storage Capacity (OSC) of catalyst Less than 0.046 g (0.000101 lb)

MONITOR RESULT

Refer to CHECKING MONITOR STATUS

CONDITIONING FOR SENSOR TESTING

HINT: Perform the operation with the engine speeds and durations described below prior to checking the waveforms of the A/F and HO2 sensors. This is in order to activate the sensors sufficiently to obtain the appropriate inspection results.

Camshaft Position Sensor
DTC P0365 Camshaft Position Sensor "B" Circuit (Bank 1) DTC P0367 Camshaft Position Sensor "B" Circuit Low Input (Bank 1) DTC P0368 Camshaft Position Sensor "B" Circui ...

Evaporative Emission System
DTC P043E Evaporative Emission System Reference Orifice Clog Up DTC P043F Evaporative Emission System Reference Orifice High Flow DTC P2401 Evaporative Emission System Leak Detection Pump Control ...

Other materials:

System Voltage
MONITOR DESCRIPTION The battery supplies electricity to the ECM even when the ignition switch is off. This power allows the ECM to store data such as DTC history, freeze frame data and fuel trim values. If the battery voltage falls below a minimum level, these memories are cleared and the ...

Inspection
1. INSPECT REAR SPEED SENSOR (a) Remove the seat cushion and seatback. (b) Disconnect the speed sensor connector. (c) Measure the resistance between terminals 1 and 2 of the speed sensor connector OK: Resistance: 1.1 +- 0.2 kΩ at 25 +- 5 °C (d) Measure the resistance between ea ...

ECM Power Source Circuit
DESCRIPTION When the ignition switch is turned to the ON position, the battery voltage is applied to terminal IGSW of the ECM. The ECM MREL output signal causes a current to flow to the coil, closing the contacts of the EFI relay and supplying power to terminal +B of the ECM. If the igniti ...

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