On the 2005 Hyundai Elantra, the P0030 is a fairly straight forward code pointing to a fault with the internal heater for the Oxygen Sensor for Bank 1 / Sensor 1. The on-board computer uses this internal heater to get the sensor to normal operating temps within a matter of seconds on cold starts. When it attempts to activate the heater and there is no repsonse, the P0030 is set. Carefully inspect the electrical connector and wire harness looking for any loose, broken or damaged wires. If the visual inspection checks ok, replacing the Heated Oxygen Sensor should solve the problem. It’s a fairly common fail item. You can find the sensor is mounted to the exhaust manifold on the side of the engine closest to the front of the vehicle. Make sure the replacement Oxygen Sensor is a “direct-fit” type sensor. If the replacement sensor needs to be “spliced” into the wire harness, this is a “universal” type and will not cure the problem. There is also a special tool that will make this job much easier: Oxygen Sensor Socket. You can usually rent this tool from most local “big chain” part stores. The tool will allow you to more easily remove the sensor without the wire harness getting in the way.
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