O2 sensors advice needed.

[greenacc]

Had the engine light come on recently and stay on. Car still drives normal. Got it scanned and there were a few oxygen sensor codes logged. Not sure exactly what the codes were.
Cleared the codes. Few days later engine light came back on no doubt for the same reason.

I've heard a lot of people on here say the oxygen sensors go and need replacing. Is that the normal first step to solve this problem? Should all 4 sensors be replaced or is it only the pre or post cat sensors that go faulty ?
Cars got over 200ks on it. V6 with no engine mods.
Thanks

 

[cewing]

See what sensors failed again with your scanner and maybe change those...

 

[monstar]

I'd get the exact code and look up what it is telling you, save flushing your dough. Likely a lean code on one or both banks. My money is on dirty MAF wire.

 

[vr304]

At 200,000ks I'd say the o2 sensors are due to be replaced probably a good idea to just replace them and be done with

 

[VS_Pete]

80000 to 100000 should be changed (life span)

 

[greenacc]

Thanks I will try cleaning the MAF wire.
Wow if O2 sensors only last 100k half the cars on the road must have dead sensors on them.

 

[vr304]

Thanks I will try cleaning the MAF wire.
Wow if O2 sensors only last 100k half the cars on the road must have dead sensors on them.

Not dead o2s but certainly not functioning the best

 

[greenacc]

Yeah ok agree, like a lot of other parts on the average car.
A set of O2's looks like it costs about $400 does that sound right? Any suggestions on best place to get them?

 

[blackve76]

Yeah ok agree, like a lot of other parts on the average car.
A set of O2's looks like it costs about $400 does that sound right? Any suggestions on best place to get them?

I had mine come on around 140K, replaced just the 2 pre cat ones and all good, the code will tell you which cat and pre/post cat

Bought mine of ebay, carful which you get there's different types re engine and year etc.

 

[greenacc]

Here's an update, doing things the hard way it seems!
Changed the 2 post cat O2s just because they are cheaper and easier than the pre cats so decided to start there. Cleared codes. Fail lol, light came back on.
Checked MAF, looks spotless but found 1 of the contacts in the plug has green corrosion on it. Cleaned it off. About to reset codes again and see what happens.
When I pulled out the O2s the colour was obviously different, driver side bank running much richer?? Could a bad MAF contact cause that ?