P0420
DTC P0420 Catalyst System Efficiency Below Threshold (Bank 1)DTC P0430 Catalyst System Efficiency Below Threshold (Bank 2)
MONITOR DESCRIPTION
DTC Detection Condition:
Monitor Strategy:
Typical Enabling Conditions:
Typical Malfunction Thresholds:
The ECM uses sensors mounted in front of and behind the Three-Way Catalytic Converter (TWC) to monitor its efficiency.
The first sensor, the Air-Fuel Ratio (A/F) sensor, sends pre-catalyst information to the ECM. The second sensor, the Heated Oxygen (HO2) sensor, sends post-catalyst information to the ECM. In order to detect any deterioration in the TWC, the ECM calculates the Oxygen Storage Capacity (OSC) of the TWC. This calculation is based on the voltage output of the HO2 sensor while performing active air-fuel ratio control.
The OSC value is an indication of the oxygen storage capacity of the TWC. 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 HO2 sensor is long, the OSC becomes greater. There is a direct correlation between the OSCs of the HO2 sensor and the TWC.
The ECM uses the OSC value to determine the state of the TWC. If any deterioration has occurred, it illuminates the MIL and sets the DTC.
HINT:
- Bank 1 refers to the bank that includes No. 1 cylinder.
- Bank 2 refers to the bank that does not include No. 1 cylinder.
- Sensor 1 refers to the sensor closest to the engine assembly.
- Sensor 2 refers to the sensor farthest away from the engine assembly.
MONITOR RESULT
Refer to CHECKING MONITOR STATUS Checking Monitor Status
CONFIRMATION DRIVING PATTERN
HINT: Performing this confirmation pattern will activate the catalyst monitor. This is very useful for verifying the completion of a repair.
a. Connect the intelligent tester or Techstream to the DLC3.
b. Turn the ignition switch ON.
c. Turn the tester ON.
d. Clear DTCs (if set).
e. Enter the following menus:
- Intelligent tester - Select: DIAGNOSIS / ENHANCED OBD II / DATA LIST / USER DATA / CAT CMPL.
- Techstream - Select: Powertrain / Engine and ECT / Data List / All / Catalyst Monitor CMPL.
f. Check that CAT CMPL (Catalyst Monitor CMPL) is INCMPL (incomplete).
g. Start the engine and warm it up.
h. Drive the vehicle at between 64 km/h and 113 km/h (40 mph and 70 mph) for at least 10 minutes.
i. Note the state of the Readiness Tests items. Those items will change to COMPL (Complete) as CAT CMPL (Catalyst Monitor CMPL) monitor operates.
j. Enter the following menus:
- Intelligent tester - Select: DIAGNOSIS / ENHANCED OBD II / DTC INFO / PENDING CODES.
- Techstream - Select: Powertrain / Engine and ECT / Trouble Codes / Pending.
k. Check if any DTCs (any pending DTCs) are set.
HINT: If CAT CMPL (Catalyst Monitor CMPL) does not change to COMPL (Complete), and any pending DTCs fail to set, extend the driving time.
CONDITIONING FOR SENSOR TESTING
HINT: Perform the operation with the engine speeds and time durations described 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.
a. Connect the intelligent tester or Techstream to the DLC3.
b. Start the engine and warm it up with all the accessories switched OFF until the engine coolant temperature stabilizes.
c. Run the engine at an engine speed of between 2500 rpm and 3000 rpm for at least 3 minutes.
d. While running the engine at 3000 rpm and 2000 rpm at 2 second intervals, check the waveforms of the A/F and HO2 sensors using the tester.
HINT:
- If either voltage output of the Air-Fuel Ratio (A/F) or Heated Oxygen (HO2) sensor does not fluctuate, or there is a noise in the waveform of either sensor, the sensor may be malfunctioning.
- If the voltage outputs of both the sensors remain lean or rich, the air-fuel ratio may be extremely lean or rich. In such cases, perform the following A/F CONTROL (Control the Injection Volume for A/F Sensor) using the intelligent tester or Techstream.
- If the Three-Way Catalytic Converter (TWC) has deteriorated, the HO2 sensor (located behind the TWC) voltage output fluctuates up and down frequently, even under normal driving conditions (active air-fuel ratio control is not performed).
Step 1:
Step 2:
Step 2(Continued)-3:
Step 3(Continued)-4:
INSPECTION PROCEDURE
HINT: Read freeze frame data using the intelligent tester or Techstream. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.