2002 Chevy Monte Carlo

2002 CHEVROLET MONTE CARLO
150,000 MILES • 6 CYL • FWD • AUTOMATIC
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YRNTU
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  • 1 POST
Computer problem
2002 Chevy Monte Carlo 6 cyl Front Wheel Drive Automatic 154 km miles

Hi,
I drive 125 km each way to work and its highway driving about 110-120 kph. If, I have to stop, in drive at the end of the exit ramp the service light comes on. The OBD II reader will say P0420 or P0440. If I put in nuetral when I stop it won't blow a code. Why does it blow a code at idle after the highway is? it one or both O'2 sensors? ANy guesses front or back snesor? This happens every day or so. I reset it with a OBD-II reader. Catalytic converter was replaced, gas cap checked and swapped out. Any ideas.

Thanks,

AL
Jun 12, 2008 at 7:16 PM
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GENERALSTAR
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  • 4 POSTS
guessing I would say the rear sensor; its switching too fast; now as far as your replacement converter was it OEM ?
Jun 24, 2008 at 7:49 PM