Fitting an O2 sensor to a car?

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Fab5Freddy

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I bought a cheap diagnostics tool as I wanted to see what my engine light was before I went to garage.
It is P2196 O2 Sensor signal stuck rich.
I changed the MAF sensor and still got problem, so presume it's the from O2 sensor.
I checked a few videos on YouTube and see what some of them say you might need to rethread the hole when replacing.
I dont know much about mechanics, so would appreciate an answer about doing out myself or just take to garage? (bearing in mind i am trying to save money by doing it myself but dont want to get into a fix that I cant mend myself)
 
It largely depends on your luck, really....some are ridiculously tight, others wind out reasonably well.
Split sockets are available so you don't need to cut the wires but I find they tend to spring open so I cut the wires and use a full hexagon socket with a breaker bar.
In some instances the exhaust has to come off you can get good access.
John :)
 
Cheers for info John - I can see the split socket head for sale and the sensor is the one before the cat and easier to get at, so maybe I will give it a go. But the tip to cut the wires is a good one, thanks
Do you use ptfe tape or white grease on it?
Why are they talking about a re-thread when you install the new one?
 
Occasionally when winding the old sensor out, the screw thread pulls out too.....if so, a special screw cutting 'tap' is used to cut or restore what's left.
By all means apply a heat resistant compound on reassembly, usually a sealing washer comes with it. It's a bit too hot for PTFE here!
Good luck with it!
John :)
 
Burnerman said:
Occasionally when winding the old sensor out, the screw thread pulls out too.....if so, a special screw cutting 'tap' is used to cut or restore what's left.
By all means apply a heat resistant compound on reassembly, usually a sealing washer comes with it. It's a bit too hot for PTFE here!
Good luck with it!
John :)
Click to expand...
John -thanks for that.
Can I just ask...if I unplug the sensor and run the OBD scanner again, would that confirm if it were that o2 sensor?
I previously thought it was the MAF and replaced it , only to find it wasn't, was I'm I'd rather be sure before buying a new one
 
The million dollar question, Freddy......unfortunately we just can't guarantee it is the lambda sensor that is at fault, as the cat plays a part too, including the after sensor if there is one. Sorry I can't say for sure but I think it is a good bet - but I've been caught out before!
John :)
 
Burnerman said:
The million dollar question, Freddy......unfortunately we just can't guarantee it is the lambda sensor that is at fault, as the cat plays a part too, including the after sensor if there is one. Sorry I can't say for sure but I think it is a good bet - but I've been caught out before!
John :)
Click to expand...
Cheers John - yes, it has another after the cat..hope I get lucky and it's the first one (for ease of getting at it, and £)
But if I dont do something about it, it might harm the cat and then be bigger £ in the longer run
 
Does the fault code not tell you whether it's the pre-cat or post-cat sensor that's stuck rich? The difficulty is that the problem could be the O2 sensor, or it could be that the engine really is running rich (e.g. because the fuel pressure is too high, or the coolant temperature sensor is telling the engine it's cold, so the ECU is giving it extra cold start enrichment). They can be quite difficult faults to nail, sometimes!
 
I recall an issue with an 02 plate Peugeot 206 - 1.1.
Engine light on, fault codes indicating the same as Freddy's problem.
New 02 sensor - just the same. New cat (Right up against the manifold, big round thing) - just the same. Unfortunately I had to bail out from that one and send it back without charge....quite a loss for me :(
Apparently the fault was cured by using genuine manufacturer parts rather than quality pattern ones - as I had done.
Therefore I am very guarded on my diagnosis in these areas!
John :)
 
Avocet said:
Does the fault code not tell you whether it's the pre-cat or post-cat sensor that's stuck rich? The difficulty is that the problem could be the O2 sensor, or it could be that the engine really is running rich (e.g. because the fuel pressure is too high, or the coolant temperature sensor is telling the engine it's cold, so the ECU is giving it extra cold start enrichment). They can be quite difficult faults to nail, sometimes!
Click to expand...

I totally take your point - I thought it was MAF , but it wasn't. And I occasionally get a dark exhaust smoke on starting and thought that maybe the fuel intake was crapped up somewhere along the line or injectors, but that was just a hunch based on my very, very limited knowledge of car engines. I put some of the petrol additive/cleaner in there and used a tank of 99% petrol to see if that helped.I cleaned the air intake and put in new air filter, changed the spark plugs and tested the ingestion coils on a multi-meter. It seems to for a while but it's not pulling great again now
My Scanner is a cheap one and maybe a garage would have one with more detail?
It says 'BANK 1 SENSOR 1'.
 
One tip is to run the engine with the 02 sensor out - really - and see if performance is restored. This negates blockage with the cat and the exhaust system downstream.
Does the engine misfire on tickover?
Which car is it?
John :)
 
I would recommend taking the car to some one who has diagnostic equipment to view live data of your engine management and sensors (and who understands what the data is telling them)They can then tell if it is a O2 sensor fault or some thing else ,I know you are trying to save costs but you can be chasing your tail if not.
 
Burnerman said:
One tip is to run the engine with the 02 sensor out - really - and see if performance is restored. This negates blockage with the cat and the exhaust system downstream.
Does the engine misfire on tickover?
Which car is it?
John :)
Click to expand...
Good suggestion, I have the socket head on order now, hopefully I can get it out
Doesn't misfire, just doesn't 'pull' too well when putting foot down.
Toyota Yaris petrol 1.3
 
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