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2003 Chevy Cavalier - Check Engine Light On

About a month ago my check engine light came on. It read that the front O2 sensor had a low HC reading. He had me pull Lucas fuel injector cleaner in the car twice. He used two cans of carb cleaner and sprayed them through the air cleaner. As a result there were two baseball size pools of black water with solid waste under the exhaust manifold. I also replaced both O2 sensors. The car ran fine for a week and the check engine light came back on. Now the O2 sensor is reading high HC. There is no rotten egg smell either.
Answer:

We would not have recommended running carburetor cleaner or Lucas through your Chevy Cavalier's intake manifold. Chances are you contaminated the oxygen sensors. The oxygen sensor triggering a lean or rich fuel system trouble code indicates high or low CO. HC is a result of the high or low CO. When a vehicle has high CO, HC is increased due to a rich misfire. When CO is low, HC may also be increased due to a lean misfire. Whether your Chevy's oxygen sensors were defective before or not, chances are they are defective now, however the test we describe below will verify their condition. The best way to get to the bottom of this is to conduct a "fuel feedback test". Have an expert smog check repair station (hopefully not one which will be running any hard solvent such as carburetor cleaner through your car's intake system) find out why your vehicle is producing high CO. The smog technician will ensure the oxygen sensors are working properly, your Chevy Cavalier's ECU is receiving signals from the oxygen sensors, the computer is computing the data properly and sending the correct signals to the fuel injectors to either increase or decrease fuel delivery to the intake manifold. At the end of the feedback test it will be know whether the high CO and HC fault is electronic or mechanical, and the technician can further diagnose the fault. posted by SmogTips Support

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