2001 Monte Carlo Running Rich

2001 CHEVROLET MONTE CARLO
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NCLARK
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I have a 2001 Monte Carlo LS with about 117,000 miles on it. After the infamous coolant/oil leak, I repaired the intake manifold gaskets. In the process, I also replaced both O2 sensors and the catalytic converter, as well as the throttle body gasket.

That being said, I am still getting error code P0420. I have noticed that my car is running VERY rich - half a talk of gas gets the car about 100 miles. There are no leaks (no fluid under the car) and no noticeable out of place smells.

Why is my car running so rich, and how can I make it return to normal?
Nov 8, 2007 at 10:27 PM
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BLACKOP555
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That code has to do with the catalyst system.

An oxygen sensor is not functioning properly
The engine coolant temperature sensor is not working properly
Damaged exhaust manifold / catalytic converter / exhaust pipe
or bad ignition timing.
Nov 9, 2007 at 6:40 AM
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NCLARK
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the coolant temp sensor apparently died before/during the gasket replacement. the $15 part fixed it right up.
Nov 10, 2007 at 12:12 PM
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BLACKOP555
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  • ASE Certified Mechanic
your most welcome :P
Nov 10, 2007 at 1:32 PM
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