One problem related to o2 sensor has been reported for the 2003 Chevrolet Impala. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2003 Chevrolet Impala based on all problems reported for the 2003 Impala.
2003 Chevrolet Impala 3. 4l is difficult to start, replaced many parts to try and fix: fuel filter, fuel pump, spark plugs and wires, oxygen sensors, fuel evap valve, and throttle control. Vehicle currently has 52,xxx miles. Security light flashes, was able to pull error code p1626: theft deterrent fuel enable signal not received. Keys are original to car, I have tried to re-learn keys to vehicle with no success. Numerous repairs are listed under this error code, including the replacement of the bcm, and this doesn't always fix the problem. This issue needs to be researched further.