Oxygen Sensor

[rkn2903]

Can someone tell me where the Oxygen Sensors or located on a 99 GMC 5.3L Vortex Seirra 1500, and what size wrench I would need to remove them? Thanks

 

RKN your from Indy? I am actually relocating there in the near future

[RyanbabZ71]

Its hard to explain but if you go under the truck you can see them

 

as far as a socket I would suggest going to an autoparts store and spending $8 and buy yourself an O2 Sensor socket. They come in very handy trust me

[rkn2903]

Thanks a lot Ryan.

[RyanbabZ71]

if you go under the truck and follow the exhaust towards the front of the truck you will see it going in. Then here is another if you look up going towards the engine bay.

[budhayes3]

There are actually 4 02 sensors, 2 before the cats and 2 after the cats. The 2 before the cats test oxygen content in the exhaust coming out of the engine. The 2 after the cats are to check the catalyst efficiency. I definitely agree with Ryanbab that the O2 sensor socket is worth every penny.

[rkn2903]

Thanks guys, I just purchase the 4 sensor, and socket the sensors are not cheap, hope the sensor don't need replacing to often.

[RyanZ71]

I'd say you shouldn't have to replace them until you get Check Engine Light. Usually your safe up to 100,000 miles though.... A faulty O2 sensor is the #1 reason vehicles failed the Emissions test when I worked at the station.

[mcreyaufmiller]

Wow, I must have a good truck. I have 130k on mine and have never replaces the sensors. Maybe I should think about doing that soon.

[budhayes3]

I've never replaced an 02 sensor as a maintenance item, I usually wait until there's a problem...like a check engine lt or decrease in performance. I've heard where some folks recommend them as maintenance, but I disagree with that. I've seen vehicles with 200k and the sensors are working fine, and I've seen new vehicles with a faulty sensor. Those sensors can get kinda pricey, especially if you replace them routinely.

 

With newer OBDII vehicles, if there's a problem with an O2 sensor, it should trip a check engine lt...whether the sensor is open or shorted, or even just "lazy". (a lazy sensor doesn't switch back and forth from rich to lean quickly enough) There are even codes for the O2 sensor heater ciruit. So, in my opinion, if there isn't anything wrong with the sensor, I'd leave it alone.

 

Just my .02.

[rkn2903]

I'm replacing the sensors because my check engine light came on, and the autzone parts guy said the code was the oxygen sensor.

[budhayes3]

I'm replacing the sensors because my check engine light came on, and the autzone parts guy said the code was the oxygen sensor.

 

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Do you know which one is bad? More than likely one of the pre-cat sensors it at fault, if you know which one is the problem you can replace that one and save yourself some cash.

[rkn2903]

I have all the sensors replaced, but the one on the driver side before the catalytic convertor I'm having a problem disconnecting it from the wiring harness, what will I have to do to disconnect the plug? Thanks everybody for everything.

[rkn2903]

[budhayes3]

Are you having a problem getting it unplugged? There my be a plastic retainer pin that you have to remove first. If there's a piece of plastic on the connector that's a different color, possibly blue, you have to pull that out first, kinda like the pin on a grenade. Then when that's out, you have to lift up on the tab that has a little angle to it, and pull the two connectors apart...it's a bit of a pain in the butt. Make sure that you pull from the connectors and not the wires, or the wires could break or come out of the connectors.

 

Oh yea, if the connector doesn't have that different colored plastic pin, then it's just a matter of prying up on the bent tab and pulling the connectors apart.

[ManyCamaroz]

I got a "Check Engine" light on occasion awhile back but could not tell a difference in performance, mileage or anything. I took it to friend with a Snap-On analyzer and it identified the left bank (driver side) downstream (behind the cat) o2 sensor to be failing. I changed it and not another probelm since. I bought a Bosch from Parts America for about $30.00, the dealer wanted about $68.00 I think. For that kinda clams

 

I would only change one out if it was faulty. Some of you guy's must make to much money or better yet let do your service work for you. lol