I have a 2003 hyndai elentra an i had both 02 sensors replaced plus flex pipe and check engine light came back on with 02 sensor error

Reset the code may not return.

Hi, guys. you can read this article first. Why check engine light is on. Maybe it is able to help you. Good luck.

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1st of all did your gas mileage drop? If It's an O2 sensor your gas mileage will be about half. If the car is running normally but you can't get the check engine Light off, It may be Simple. Most cars these days have an Oil Life Sensor that needs to be reset after Oil Changes. Turn your Key On , But Do not START. Pump your Accelerator to the Floor 3 Times In 10 Seconds and turn the key off. Start It up Again And See if that was it.

check engine light on when tested it says bad o2 sensor did you replace 02 sensor it takes driveing it so many miles before light will go off give it couple days you dont need cadillac converter check engine light will go off cv joint they click as you turn dont let a mechanic sell you something you dont need its very rare for cadillac converters to go bad its common for o2 sensors to go bad like yours did but when 02 sensors are replaced it takes driveing it for awhile before it resets itself you also have more then one 02 sensor was then wrong one replaced they screw into your exaust manifold

Replacing an O2 sensor generally is "fixing the symptom" instead of fixing the cause. A good O2 sensor will often trigger a code if the exhaust mixture it is "seeing" is out of its range to adjust. If the pipe was bad when the sensor was changed, or if another part of the engine management system is out of range, it can cause the new sensor to fail or trigger the check engine light. In your case, I'd clear the codes and see if that helps. If not, you likely will need to do better diagnosis and perhaps again change the sensor if everything else checks out as good.

you shoul replace all 4 then remove batt cables hold together 10 sec reinstall cables

The sensor is located behind the catylst depending on how many o2 sensors you have. make sure there are no exhaust leaks.

the sensor bank is the exaust manifold the # 1 is left side #2 is right side. they should be located right after the exaust manifold on the pipe it's self. all you have to do is unplug them and remove for replacement.

it means you have a bod O2 senser the front one as your car has two or three for a v6 but it will be the first one one in the pipe on the front side of a gm product or if your exhaust pipe comes off the back i.e. 2.3 it will be the one in the manifold itself ohh do not forget to check the plug first sometimes an over enthusiastic mechanic unplugs or tampers with these to get you to do more work check the plugs well and wires they are easily fixed