I had to replace the upstream O2 sensor on a Hyundai 2005 Elantra. My trusted mechanic advised me to go with a genuine OEM replacement O2 sensor, instead of any aftermarket substitutes that “may” work. I agreed, but it was pricey at about $300 for the genuine part alone. That said, for future knowledge…
I wish to know how the sensor goes bad. Is it choice of gasoline? Carbon build-up? Or, natural wear and tear I cannot avoid? In other words, is there anything I can do to help maintain these sensors? I believe there is one upstream and two downstream sensors. I would hate to go through thi$$$ again! :smack: Please advise me!
Been a while since I turned a wrench professionally, so forgive me if Im remembering incorrectly.
Heat, vibration, crud in combination are the primary contributors for the sensor itself. There may be varying other factors depending on age and maintenance.
Realized I didn’t fully answer the question, as far as what you can do, regular maintenance is about all really. That should include inspecting all wires and hoses for wear and security against moving and at the connections.
O2 sensors are very sensitive to contamination. If you use silicone sealant or lubricant anywhere in the same ZIP code you may cause problems. There are some sealants labelled as “O2 sensor safe,” but you have to look for that.
They are also sensitive to antifreeze, so if your engine is leaking coolant into the combustion chamber, this may be a cause.
Zinc is another concern. Zinc dithiodiphosphate (ZDDP) is an additive in motor oils, so if your engine is burning oil, this may also be a cause. The SAE specs for motor oil have called for lower and lower quantities of ZDDP over the years to promote the endurance of O2 sensors and cats in more vehicles, but everything has its limits.
Other than that, they do simply age over time, and I think it’s not uncommon to replace one after 100K miles or so. If wires break you get no signal, but cumulative contamination can result in a sensor that responds too slowly, which will throw a different code. Either way, you need to replace.
You need the upstream O2 sensor for your engine to work properly, or rather, for the computer to tell it to work properly. But if you live in an area without EPA testing you can have the rear sensors ‘tuned out’. This is how cars that have after-market exhausts or headers deal with the elimination of the rear sensors. Cost to tune out the rear ones would be about the same as you paid to replace the front one, which you need.
How many miles are on your 2005 Elantra? As already stated, sometimes the sensors just go bad, without a major cause from your engine. But if you lose a second upstream O2 then you have something wrong in your engine that is causing it and you probably want to replace the car, not another sensor.
Jinx, in your case they may have been bad from the outset. I had a 2003 Hyundai Santa Fe where the oxygen sensors started going bad after a couple of years. The first time it happened, the dealer explained to me that Hyundai knew they were bad but it wasn’t a serious enough issue for a recall, but that they would replace them under warranty when they went bad.
(What they never specified was which warranty. I assumed 10/100,000 engine and power train, but as I found out when sensor #3 finally went bad, they’re actually covered under the 3/36,000 bumper to bumper, which had expired.)