DTC P0420:00 [L8, LF]

id0102b1859400

DTC P0420:00

Catalyst system efficiency below threshold
DETECTION CONDITION
•  PCM compares number of A/F sensor and HO2S inversions for a predetermined time. PCM monitors number of inversions rear sides performs while front side inverts for specified number of times when the following monitoring conditions are met. detects inversion ratio is below threshold, PCM determines that catalyst system has deteriorated.
MONITORING CONDITION
―  Calculated TWC temperature: more than 400 °C {752 °F}
―  Engine speed: 1,500—3,000 rpm
―  LOAD: 17—50 % (MTX), 20—50 % (ATX) (at engine speed 2,000 rpm)
Diagnostic support note
•  This is an intermittent monitor (Catalyst).
•  The MIL illuminates if the PCM detects the above malfunction condition in two consecutive drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM.
•  PENDING CODE is available if the PCM detects the above malfunction condition during the first drive cycle.
•  FREEZE FRAME DATA is available.
•  The DTC is stored in the PCM memory.
POSSIBLE CAUSE
•  TWC deterioration or malfunction
•  Exhaust gas leakage
•  Loose A/F sensor
•  Loose HO2S
•  PCM malfunction

Diagnostic procedure

STEP

INSPECTION

ACTION
1
VERIFY FREEZE FRAME DATA AND DIAGNOSTIC MONITORING TEST RESULTS HAS BEEN RECORDED
•  Has FREEZE FRAME DATA been recorded?
Yes
Go to the next step.
No
Record the FREEZE FRAME on the repair order, then go to the next step.
2
VERIFY RELATED SERVICE INFORMATION AVAILABILITY
•  Verify related Service Information availability.
•  Is any related Service Information available?
Yes
Perform repair or diagnosis according to the available Service information.
If the vehicle is not repaired, go to the next step.
No
Go to the next step.
3
VERIFY RELATED PENDING CODE OR STORED DTC
•  Switch the ignition to off, then to the ON (Engine off).
•  Verify the related PENDING CODE or stored DTCs.
•  Are other DTCs present?
Yes
Go to the applicable DTC inspection.
(See DTC TABLE [L8, LF, L5].)
No
Go to the next step.
4
INSPECT EXHAUST SYSTEM FOR EXHAUST GAS LEAKAGE
•  Visually inspect exhaust gas leakage in the exhaust system.
•  Is there exhaust gas leakage?
Yes
Repair or replace the malfunctioning part, then go to Step 7.
No
Go to the next step.
5
INSPECT INSTALLATION OF HO2S
•  Inspect the HO2S for looseness.
•  Is it normal?
Yes
Go to the next step.
No
Retighten the HO2S, then go to Step 7.
(See AIR FUEL RATIO (A/F) SENSOR, HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION [L8, LF, L5].)
6
INSPECT TWC
•  Clear the DTC using the M-MDS generic OBD function.
•  Switch the ignition to off then back to the ON.
•  Inspect the TWC.
•  Is it normal?
Yes
Go to the next step.
No
Replace the TWC, then go to the next step.
(See EXHAUST SYSTEM REMOVAL/INSTALLATION [L8, LF, L5].)
7
VERIFY TROUBLESHOOTING OF DTC P0420:00 COMPLETED
•  Make sure to reconnect all disconnected connectors.
•  Switch the ignition to ON (Engine off).
•  Clear the DTC from the memory using the M-MDS.
•  Perform the A/F sensor heater, HO2S heater, A/F sensor, HO2S, and TWC Repair Verification Drive Mode.
•  Is the PENDING CODE for this DTC present?
Yes
Replace the PCM, then go to the next step.
(See PCM REMOVAL/INSTALLATION [L8, LF, L5].)
No
Go to the next step.
8
VERIFY AFTER REPAIR PROCEDURE
•  Perform the “AFTER REPAIR PROCEDURE”.
•  Are any DTC present?
Yes
Go to the applicable DTC troubleshooting.
(See DTC TABLE [L8, LF, L5].)
No
Troubleshooting completed.