Oxy Sensor Question

[tlong]

There are 3 of these rascals on a '96. Are they 100% good until they fail setting codes or can they gradually erode performance? They are important to the brain I would say. Is there a way to check them or do y'all just change them out at a given mileage? 58k miles and runs scary good. It ain't broke so should I fix it anyhow?

 

[JonM]

I would say the O2 sensor is the most important sensor in the car... It controls whatthe ECM does. I got this off another site

Modern, sophisticated cars don't require as much servicing as older models. Still, if your car was built since the mid-1980s, chances are it has an oxygen sensor in its exhaust system. You may never have encountered an oxygen sensor before, but it's a part which requires periodic replacement as part of your routine servicing. Otherwise, you could experience poor vehicle performance on the highway.

An oxygen sensor is designed to measure the oxygen content of a car's exhaust gases. This information helps the engine-control computer regulate the mixture of air and fuel burned in the engine to provide an optimal balance of power, economy and clean exhaust.

Oxygen sensors are relatively simple to replace with most models costing $50 to $100. Replacement intervals range from 30,000 to 50,000 miles, and are generally listed in the owner's manual.

While on-time oxygen sensor replacement is vital, many motorists don't have the job done when they should because there isn't a noticeable difference in the way a car drives when the sensor stops functioning normally. Some motorists may even skip oxygen sensor servicing on purpose, figuring there's no need to do anything until the car starts to "act up".

Either way, they're making an expensive mistake. An engine may use too much fuel when the oxygen sensor isn't working. This doesn't just hurt economically, it also creates dirty exhaust, polluting the air.

An alert motorist may notice worsening fuel mileage or driveability problems and have the sensor changed. But he adds that since most drivers don't notice anything wrong until driveability suffers, dirty exhaust may already be coming from the vehicle creating an environmental problem.

Seeing The Light
Because oxygen sensor replacement is important, many car makers include hard-to-ignore reminders, like a glowing red light on the instrument panel as the sensor replacement interval approaches. The light keeps glowing (while the ignition is on) until the car is serviced.

Another Indicator
Some cars' instrument panels include a different dash light meant to indicate problems with components of the engine control system, including the oxygen sensor and other items. Typically, these lights are labeled "service engine soon," "check engine," "power loss," or something similar. If your car uses this system (check your owner's manual), you still must replace your oxygen sensor at the mileage interval specified by the car maker.

The light won't come on simply to let you know it's time to replace your oxygen sensor, it's up to you to keep track of when the sensor needs servicing.

Since its glowing may indicate one or more of a number of problems, a service technician will have to 'interrogate' your car's computer to find out which system or systems aren't working correctly. Further tests may then be needed to find out what's wrong with the affected system or systems."

If you're a serious do-it-yourselfer (DIYer), consult the correct shop manual for your car if this light comes on. In many cases, the manual will explain step-by-step procedures to make the light signal (using semaphore-type flashing codes) where the problems lie.

Care About Your Car
Routine auto servicing is different than it was a few years ago. Though in most respects it's easier, it still comes down to paying a little now or a lot later.

Today's high-tech cars don't need constant attention, but there hasn't been a car invented yet that can take care of itself. Make a point of learning your new car's service requirements. As with the oxygen sensor, something you've never heard of before may need occasional attention.

 

[Vis Croceus]

There are 3 of these rascals on a '96. Are they 100% good until they fail setting codes or can they gradually erode performance? They are important to the brain I would say. Is there a way to check them or do y'all just change them out at a given mileage? 58k miles and runs scary good. It ain't broke so should I fix it anyhow?

There are 4 on a 96.

On most of my cars I replace them around 60k intervals. They do gradually deteriorate. Some cars have really expensive O2s (like $200-300/ea) and those I just wait until they get bad enough to throw a code.

On the 96, if you want to economize, the rear two do not affect engine tune, so you could just replace the fronts.

 

[Vis Croceus]

I just found this same information on several sites:

"Unheated 1 or 2 wire wire O2 sensors on 1976 through early 1990s vehicles can be replaced every 30,000 to 50,000 miles. Heated 3 and 4-wire O2 sensors on mid-1980s through mid-1990s applications can be changed every 60,000 miles. On OBD II equipped vehicles (1996 & up), a replacement interval of 100,000 miles can be recommended."

 

[tlong]

Thanks fellows. I may do the pre-emptive maintenance on the front 2 with these miles. My friend has one of those special sockets for them. That and the arms of Hercules and they might come out.

When the Corsas went in there was only one 02 sensor downstream from cats. And what a beeeeotch to remove.

 

[WradDad]

Well thanks to tlong's help, I'll be replacing the left-side cat soon. Sounds like while I'm under there, I' should replace at least the leading O2 sensors!

 

[PLRX]

More LT4 news for me... I did not know the 96's have 4-O2 Sensors....Why?

 

[Vis Croceus]

More LT4 news for me... I did not know the 96's have 4-O2 Sensors....Why?

All OBD2 vehicles have O2s behind the cats to monitor the condition of the cats.

 

[tjwong]

Put it on a Snap-On MT2500, "If within Range it aint Broke Don't Fix It" gmjunkie!!

I don't totally agree with that statement. Sometimes even if the sensors pass a Scan tool test, be it from a MT2500 or a GM TECH2 the sensor can still be lazy. On a stock LT1 series engine or for that matter any engine using an O2 sensor. If the fuel trims look out of spec and if everything else is OK then the first thing I would be looking at replacing would be the O2 sensors, especially if they are high miles on them.

 

[Lvycravsit]

Have similar problems with my '96

I am new to this forum and need some advice. My '96 has had problems with the O2 sensors and the SES light staying on. This has been going on for several months and the sensors have been replaced at least twice, replaced a couple spark plugs, the Optispark distributor, PVC valve, and the computer, etc. I get the car back from the shop and it may run fine for 25 miles. Get in the car and start her up and on comes the light again. I have also noticed this last time that I am averaging about 3-4 miles per gallon less on fuel usage. Originally, it coded Bank 2, Sensor 2, but the last time, it showed that one was dead (although just replaced) and the other two were so erratic on the readout that the car never should have been running in the first place. This is what caused them to replace the computer, thinking it was sending out errant codes. The distributor was replaced because somehow it got wet. Another issue I have is that the overflow coolant tank has been emptying out. The radiator system has been pressure tested 2-3 times and is showing no leaks, but this last time they replaced the cap thinking it wasn't tight and allowing the steam to escape and then sucking up the reserviour contents. I thought there might be a leak that was causing these sensors to get gunked up. Does anyone have any thoughts....the car goes back to the shop tomorrow and if they still can't fix it, I am finding another shop!

 

[Lvycravsit]

Still having problem with SES light

Well, the car went in the shop and they cleaned all the ground connections for lack of any other possible fix. This time it popped up with about 7 different codes relating to the O2 sensors, etc. As usual, drove the car home and to work the next morning --- no light. On the way home from work the stupid light came back on. Someone sent me an email suggesting it could be due to a loose gas cap, so I have made sure I tightened it. They said it may take several driving cycles for it to clear itself, so I am waiting to see if that happens. This is getting soooooo frustrating!

 

[Edmond]

I thought that the O2 sensors had a certain threshold they ran within and when they ran below that threshold, that's when the code pops up.

 

[KOPBET]

I would have the coolant tested for exhaust gases. Antifreeze will kill O2 sensors.

 

[WhalePirot]

the arms of Hercules and they might come out.

I trust this is in jest, as opposed to using some lube to soak them free.

 

[tlong]

They are supposed to have a heat resistant thread lube, but still quite a feat after 10 years. The pre-soak cycle is recomended.