Help with codes

[aleks88]

I have a 2002 camry and I get a check engine light and check the code it is p0420. Can anybody explain the code and what I have to do to repair it.

Thanks
Alex

[somick]

Catalyst System Efficiency Below Threshold

I would check O2 sensors.

Sam

[gene112601]

Originally Posted by aleks88

I have a 2002 camry and I get a check engine light and check the code it is p0420. Can anybody explain the code and what I have to do to repair it.

Thanks
Alex

Catalyst System Efficiensy Below Threshold (Bank1)

[toyomoho]

The cars emissions trouble-shooting system has no way to directly test the CAT for efficiency and thus report that it IS the problem. The system checks CAT performance indirectly.

P0420 usually means there is a problem with the 02 (A/F) sensors, their circuits (wiring) or the CAT. The exhaust system has 02 (A/F) sensors before and after the CAT. The signal outputs from the two sensors are compared by the ECU to determine the efficiency of the CAT.

If the signals are of the same amplitude, the ECU triggers the code. Meaning there is a problem with either of the sensors, their wiring or the CAT is operating below efficiency. There are specific trouble codes for the sensors but none to indicate the CAT is bad.

If no other codes are indicated pointing to a 02 (A/F) sensor then running down the problem is harder without doing some kind of diagnostics. The Toyota dealer or any shop equipped with the right type of equipment can determine if it is a sensor or CAT problem without guessing.

The CAT should have a mandated EPA extended warranty period of up to 8Y and 80K miles.