Toyota Repair: 2002 toyota camry code p0420, 2002 toyota camry, toyota camry

Question
QUESTION: i have a 2002 Toyota Camry. the check engine light has been coming on intermittently. the check engine light comes on when we use a lower grade of fuel 87 oct. and when the tank gets down to a quarter full. if i fill it with 89 oct and add a can of gas treatment the light usually goes back off within 20 miles of driving. when the check engine light is on the code is p0420. catalysis inefficiency.

ANSWER: This is a common problem on the camrys, the exhaust manifold with the converter will probably need to be replaced. The warranty on the catalityc converter is 8yrs/80/000 miles.

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QUESTION: why? the converter? either it is bad or its not. doesn't add up or  explain why the light goes off and not just stay on.

Answer
The p0420 code is directly related to a malfunctioning cat converter, the reason the light will turn on/off is that after a few drive cycles the computer may reset because the problem is intermittent and after the computer monitors the cat converter again and it fails it will turn the check engine light on again.