2000 Toyota Camry

MANNY BETTENCOURT

MEMBER
2000 TOYOTA CAMRY
4 CYL
FWD
AUTOMATIC
136,000 MILES

My check engine light is on. The code is 0420. I have replace the catalytic converter (one month ago), the front oxygen sensor (2 years ago), the egr? Valve (2 years ago) and the rear oxygen sensor (1 week ago) and the light still comes on. I've been told that the problem may be that the catalytic converter I bought (from Autozone) is an after market product and that Toyota's require OEM converters directly from Toyota. I have spent over $900.00 trying to get this fixed to pass emission inspection. Would you please advise me on what I should try next.
Thanks,
Manny

1 Reply

BMRFIXIT

MECHANIC
19,053 POSTS

DTC P0420: CATALYST SYSTEM EFFICIENCY BELOW THRESHOLD
Circuit Description
ECM compares waveform of Air/Fuel (A/F) sensor (located in front of catalytic converter) with waveform of heated oxygen sensor No. 2 (located behind catalytic converter) to determine if converter performance has deteriorated. If both waveforms change at similar rate, catalyst performance has deteriorated. DTC is set when A/F sensor and heated oxygen sensor No. 2 waveforms have same amplitude after vehicle is driven for 5 minutes at 20-50 MPH. Possible causes are:
� � � Exhaust system leak.
� � � Defective A/F sensor.
� � � Defective heated oxygen sensor No. 2.
� � � Defective catalytic converter.
Diagnostic Aids
Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected.

Diagnosis & Repair
1. If other DTCs are displayed, diagnose and repair those DTCs first and retest system. If only DTC P0420 is displayed, go to next step. 2. Check exhaust system for leaks. If problem exists, repair as necessary. If problem does not exist, go to next step. 3. Check A/F sensor circuits. See DTC P0125: INSUFFICIENT COOLANT TEMPERATURE FOR CLOSED LOOP FUEL CONTROL. If problem exists, repair as necessary. If problem
does not exist, go to next step. 4. Check heated oxygen sensor No. 2 circuits. See DTC P0136: HEATED OXYGEN SENSOR NO. 2 CIRCUIT. If problem exists, repair as necessary. If problem does not exist, replace catalytic converter.