O2 sensor failure

[chuntington101]

Ok what exactly causes an O2 sensor to fail?

A mate has just got an Astra GSI (the 2.0turbo) and the only mod he has done is a dump valve. From day one he has been having problems with the car. Vauxhall have replaced the engine wiring loom and a boost sensor so far still not solving the problem!

Now they recon it’s an O2 sensor (I think the second one), saying its not giving out any signal.

So what causes these to go? I doubt it could be the dump valve (could it?)! so what “could” it be?

Thanks for any help or info you guy and girls could give.

Chris.

PS. Also Vauxhall are currently refusing to do the work under warranty even though the car is only in the first 2 weeks of a year Vauxhall warranty! Are the O2’s covered under warranty? If not how come???

[GreenV8S]

Contamination, or soot, seem to be the usual causes. For example some types of silicon will poison them, and mustn't be used on the engine. The soot physically prevents the sensor from seeing changes in the exhaust gas composition so it gets slower and slower and eventually stops working. The people who changed the sensor should have been able to give some idea of what was wrong with the old one, particularly if they check before it has completely failed.

[chuntington101]

thanks green i will let him know. the problem is vauxhall are doing the work themselves so i doubt there will be any feed back on if that was the problem or not!

thanks Chris.

[steve_d]

chuntington101 said:

thanks green i will let him know. the problem is vauxhall are doing the work themselves so i doubt there will be any feed back on if that was the problem or not!

thanks Chris.

There had better be some feedback if your mates paying for it. I would also insist on keeping all the parts they take off.

Steve

[stevieturbo]

chuntington101 said:

Now they recon it’s an O2 sensor (I think the second one), saying its not giving out any signal.

So what causes these to go?

IS it or isnt it giving out a signal ? Its not a difficult thing to determine.

Is there any voltage present ?? or is the voltage from it very low....

Maybe its just reading what it sees, and the fault is elsewhere...perhaps a faulty cat ??


And what exactly is the problem ??? you dont mention.

The problem with diagnostic scanners, is that there are far too many idiots out there, who dont know how to use them, and interpret what it tells them. Many just blindly see a fault code, and think replace this part....So often that isnt the case.

And why wuldnt they cover it under warranty ?? If they dont, I think it would be worth seeking legal advice...

Might also be worth a search through here.
www.ilexa.co.uk/forum/index.php?board=21.0

[eliot]

replacing o2 sensors seems to be a default step most garages take when they cant figure out whats wrong.

[chuntington101]

steve and eliot i agree! i dont think vauxhall have a clue what the actual problem is and are just replacing parts till they find the right one!

the only problem he is having with the car is the engine light. he says it feels a little more sluygish but i think its more in his head.

steve the cat could be gone, but its not that old a car (one of the astra G's cant remeber the plate). the prievous owner did have a boy racer exhaust on there. could that make a diffrence (ie cause the sooting up?)?

thanks again chris.