Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

O2 sensors for 2003 Hyundai Elantra

Hi. I’ve been looking around for the right o2 sensors for my wife’s 2003 Hyundai Elantra. I need both the upstream and downstream sensors. There are so many choices (1, 2, 3, and 4 wire universal, direct replacement, etc.), plus I don’t want to spend a ton of money, and I have to act fast because she has a little over a week before her inspection sticker expires. Can anyone help?


When it comes to replacing O2 sensors, you want to install an OEM type aftermarket sensor. This is just a plug and play affair. You’ll pay a little more, but you’ll only do the job once.


How do you know that you need to replace these O2 sensors? A lot of people have the impression that there are error codes that tell you that O2 sensors are bad. There are no such codes. A lot of O2 sensors get replaced b/c they are just doing what they are supposed to (basically reporting on exhaust conditions). Exhaust conditions can be off for many reasons.

So if you don’t want to spend a ton of money make sure that you really do need O2 sensors.

If you have some specific error codes to share people can provide suggestions on diagnosis.

The O2s should really not be bad on an '03 car unless there is something in the history that killed them. Poor engine running with a CEL on for months on end, coolant entering the intake tract or combustion chambers, etc.

Why do you think you need any of them?

Honestly, because of those codes. I don’t have them to share; this was a while ago when I checked. It is a flood recovery vehicle that we bought from my friend’s dad, who rebuilt the car after the flood. It was his father’s before that. All I know is that something is triggering the “check engine” light, and it at least needs to be turned off long enough for the car to pass inspection. Just plugging it in to a computer and turning it off works, but it is very unpredictable about when it turns back on again, and it always does.

With a flood car it could be anybody’s guess. About all I can recommend is that the car be scanned for codes and go from there.
AutoZone or other similar car parts houses will scan the car for free.

Codes only provide a starting point for diagnosis and having O2 codes present does not mean that the O2s are at fault. While flood water could kill the O2s the problem could also be caused by an engine vacuum problem, corroded wire connections in the O2 circuits, etc., etc.