What causes the check engine light to come on on my dodge grand caravan?

2000 DODGE CARAVAN
325,000 MILES • 6 CYL • FWD • AUTOMATIC
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PAPET
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i have changed the cat converter, oxygen sensor and the EGR valve already and has been reset. but after a couple of days, the check engine light is back. what must be the real problem on my vehicle?
Sep 28, 2011 at 4:39 AM
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JACOBANDNICKOLAS
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I need to know what trouble code shows up when the computer is scanned. Do you know?
Sep 28, 2011 at 5:21 AM
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PAPET
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the code is P0420. thanks.
Sep 28, 2011 at 5:36 AM
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JACOBANDNICKOLAS
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That is for the catalytic converter. Considering you have already replaced the converter and O2 sensor, there is most likely a wiring issue. Have you checked wiring to the sensor for damage, corrosion...? Has you check (with a live scanner) the parameters of the sensor? Is it within spec?
Sep 28, 2011 at 5:42 AM
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PAPET
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do you mean the oxygen sensor wirings? thanks once again.
Sep 28, 2011 at 7:13 AM
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RIVERMIKERAT
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Yes, O2 sensor wiring.
Sep 29, 2011 at 7:49 PM
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