O2 HEGO Sensor nightmare, please simplify for me!

[RacerJason]

I've owned my 1999 SVT for... let's say seven years. Currently has 85K miles on it. Do 90% of the maintenance on it myself but am stumped when decipering the number and location of sensors to do with emissions.

IDS Diagnosis=

"KOEC"
P0133
P0171
P1131

"Needs both FRT HEGOS, Air Filter that fits properly and MAF cleaned."

Those were the notes from the stealership when they tested my emissions last Thursday. Which O2's or other sensors am I to replace? I removed intake to throttle body and cleaned it all last night including using spray electrical contact cleaner on the MAF and I will check all the hoses for potential vaccum leaks, etc.

 

[BrApple]

I don't recall all of the codes off the top of my head but it would seem like the up stream O2 sensors need to be replaced.

 

[B3NN3TT]

The 0133 and 1131 are both referring to Bank One Sensor One, which is located on the back side of the engine, behind the coil pack, above the steering rack. Pretty hard to reach comfortably.

The 0171 refers to a lean condition, which may be caused by vacuum leaks, or a dirty MAF. Leave that one until later, and see if it goes away.

 

[amc49]

Actually, I would go after the lean condition first. A most common problem on cars nowadays is leaking hose which can do that easily and produce O2 codes too. If live data output shows voltage stuck low then they could say sensors bad when not, commonly done all the time to pump up profits for lazy mechs. Think about it, what'r the odds of 2 sensors going bad at same time unless someone forcefeeding wrong fuel or somesuch? I find that most people change O2 sensors at the drop of a hat, they really fail much less than that. You guys on this site go plumb crazy doing it, often for no reason other than it makes you feel better.

Running codes is not testing emissions, two different things.

 

[BrApple]

my only issue with that is I have gotten lean codes for one bank and replacing the O2 sensor has foxed the problem. there where no other issues.

but yes, check for vacuum leaks first.

 

[amc49]

I have no problem with that, but I sell O2 sensors to people all day long that just change them left and right, I also see on this site exhibition of same think/speak. If you have high mileage on them fine, but if you've done them recent then look somewhere else. There is a tendency nowadays to listen to the mech or close friend or somesuch that insists they know what the problem is 'so I'm gonna throw that part at it because he told me to'. What ever happened to intelligent troubleshooting? It's just so much easier to screw in a part than have to look for the trouble, isn't it? Read the site and see how much trouble guys have just trying to figure out how to do simple vac leak checking. Lean code generally will mean stuck low volts and no switching, in my experience it has most of the time been a vacuum leak. You can whip out a $10 voltmeter and patch into O2 output to check that switching. If the vacuum leak is not major, it could still be present even though the new O2 seemingly cured it because the new one switches faster and the faster response can keep adjustment just within fuel trim limits where the other couldn't because too slow. Meaning the leak could STILL EXIST when seemingly fixed.

In this case the guy DOES need sensor probably, even though many can go longer than that. 85K about time to start thinking about them as a possible problem causer.

Disregard my rant, the troubles with people and sometimes lemming-like thinking still fresh in my mind. It just lead to me getting into it with a customer over samesuch mindlock and before all over the police were involved.