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) |
|
|
P0430 |
OSC value is smaller than standard value under active air-fuel ratio control (2 trip detection logic) |
|
HINT:
- Bank 1 refers to the bank that includes cylinder No. 1.
- Bank 2 refers to the bank that does not include cylinder No. 1.
- Sensor 1 refers to the sensor closest to the engine assembly.
- Sensor 2 refers to the sensor farthest away from the engine assembly.
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:
Adjustment
1. VEHICLE PREPARATION FOR FOG LIGHT AIMING
Prepare the vehicle:
Ensure there is no damage or deformation to the
body around the fog lights.
Fill the fuel tank.
Make sure that the oil is filled to the specified
level.
Make sure that the coolant is fi ...
Throttle Actuator Control Motor Circuit
DESCRIPTION
The throttle actuator is operated by the ECM and opens and closes the
throttle valve using gears.
The opening angle of the throttle valve is detected by the Throttle Position
(TP) sensor, which is mounted
on the throttle body. The TP sensor provides feedback to the ECM. This ...
On-vehicle inspection
1. INSPECT SIDE AIRBAG SENSOR (VEHICLE NOT
INVOLVED IN COLLISION)
Perform a diagnostic system check.
2. INSPECT SIDE AIRBAG SENSOR (VEHICLE
INVOLVED IN COLLISION AND AIRBAG HAS NOT
DEPLOYED)
Perform a diagnostic system check.
When the center pillar of the vehicle or ...
