Buy O2 Sensors in Pairs - Is This Legit? (Searched and read a crap ton)

**sparkydog** · 06-06-2017

I'm buying a downstream O2 sensor from Rock Auto and they are "suggesting" that it is best to replace both up and downstream together. Is this true?

FWIW I searched for thread titles that contained "O2" and/or "sensor" and then read the O2 ones 9 pages in on the search results. That was about 20 threads worth of O2 Sensors (yawn). They were all about brand names to buy, troubleshooting, location, removal tools, blah blah.

And FWIW part deux the reason I'm buying downstream is I got the fault code several times. Have tried cleaning contacts in the connector, inspected condition of wires, cleared codes and every time the code came back after another 100-200 miles. (At least I got it to stay off long enough to pass Calif smog!

) Car has about 130k on it.

Thanks for any advice guys!

**Scottydoggs** · 06-06-2017

if you got 50,000 miles or more on the upstream, may as well change it. if its been changed already theres no reason to change it now with the rear one.

**cheatah faheatah** · 06-06-2017

Save the dough. No code=no swap imho. Hell, I don't even change wipers in pairs. New one goes on my side, and move that one to passenger side.

**CHI2000GTP** · 06-07-2017

Originally Posted by cheatah faheatah

Save the dough. No code=no swap imho. Hell, I don't even change wipers in pairs. New one goes on my side, and move that one to passenger side.

I take the opposite approach. I like changing everything on the car in pairs, when it comes in pairs. Brake pads, brake rotors, wipers, tires. The O2 sensors are "trusted sensors" meaning the PCM trusts they're data output no matter what! It could be feeding the PCM dog shyt and the PCM would nod with approval. Change both of them, I say.

**CHI2000GTP** · 06-07-2017

Also, SparkyDog. I have been following your builds, Halfbreed and now the 944. You're a fukking lunatic man. Incredible amounts of work. I check up on our 944 thread often, like most I don't comment, just admire from afar. Watching your progress helps keep me motivated with my GTP rebuild. Ha! Keep up the good work!

**sparkydog** · 06-08-2017

Thanks for the compliment Chi Guy - it always helps to know I'm being followed (in a good way)!

And thanks to all for your thoughts - looks like we're pretty much split down the middle on save money or be cautious and swap both. Maybe I'll just flip a coin on this one!

Thread: Buy O2 Sensors in Pairs - Is This Legit? (Searched and read a crap ton)

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