2 oxygen sensors on 1999 SL1 ?
 

Hi all,

I bought a 1999 Saturn SL1 with the SOCH engine for $900. It's a decent driver, automatic tranny, but needs a few things. Has 211,000 on the clock lol.

The red dash idiot light is on for the ETCS or some coolant issue. So I just ordered the brass version of the ETCS as well as a new thermostat from Rock Auto (btw I got the AC Delco 12T49D themrostat that has the entire water-pipe end assembly so I assume I won't need that carboard tube thing to remove the internal part of the stat from the housing, correct? The temp gauge swings wildly from 1/4 or less to 1/2 on the nose, but never goes above 1/2. The "heat" is just lukewarm at best though, so i'm hoping new ETCS and new thermostat cure this issue. I;ve heard the temp gauge should read a steady 3/8 on the nose under normal conditions.

Now on to the exhaust system. The former owner ran over a huge chunk of ice and broke the pipe underneath past the cat. His brother did some nice welds and all and it doesn't seem to be leaking- no "pops" or issues. I do need some brackets and stuff though.

So he told me the oxygen sensor that it located in the exhaust pipe under the car snapped off when he hit the ice. I figure it was kinda like a spark-plug looking thing that sticks out a bit from the pipe.

But everything I've read on google etc says the oxygen sensor is on the exhaust manifold/header right by the engine. So is the senor in the exhaust pipe underneath the car (just past the cat) something else, or is there no sensor there and the former owner is mistaken? The check engine light is on BTW but the car ides and runs smooth as silk, so do I even need to worry? Is the sensor very important? The car has a good NJ inspection sticker that runs until late 2015 so i don;t want to spend $$$ if I don;t have to since i won't get emission tested for a long time and the car might die before then lol.

thanks

scotty

There are two oxygen sensors. The first one is on the exhaust manifold in front of the warm up cat. It does all the work for setting the A/F ratio etc. The second one is after the cat on the exhaust pipe and it monitors the cat to see if it is doing its job.

Both are required for OBDII compliant vehicles.

If you decide to replace the rear o2, warm the car up a bit and wear gloves.

This will help you to break what is a nasty rusty connection. Don't burn yourself

Thanks for the responses. I can't seem to find part # or info for the one in the exhaust pipe under the car.

Also what tools do I need for the underneath one? Does it just screw in like a spark plug ?

you need an offset O2 socket that has a slot in the side for the wire to pass through.

However if it is truly snapped off the wire is probably hanging with the snapped off piece and this may not be an issue. Gotta get under there to see what's what.

But you WILL need the tool to put the new one back in. Available at any auto parts store. Not too expensive