Oxygen sensor

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kingdoodlesquat - 11 Mar 2007 23:00 GMT

Hello all,

I've recently bought a '98 900S turbo & was having a look at the fuses by
the passenger door (like you do) & have discovered that fuse 38 for the
oxygen sensor has blown it fuse. First off, what does the sensor do & is it
the same thing as the lambda sensor? Second thing, is this likely to cause
any damage if it's not working?

It runs really wells at the moment & I've not noticed any drop in
performance, so I'm at a loss at what the problem really is.

tia

kds

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Fred W - 11 Mar 2007 23:35 GMT

> Hello all,
>
[quoted text clipped - 10 lines]
>
> kds

First off, yes the O2 senosr is the same as a "lambda" sensor.
The only part of the sensor that gets power is the heater. The purpose
of the heater is to get the sensor up at operating temperature faster so
that the ECU can go into closed loop mode faster. This design minimizes
the higher emmissions period of "open-loop" warm-up mode. If there is a
problem with it you would notice it about 3-5 minutes after a cold start
when the ECU tries to switch over to closed loop.

Normally, you would then get a check engine fault of some sort. You may
want to verify that you Check Engine lamp is OK, and has not been
defeated by the prior owner or unscrupulous salesman.

Signature

-Fred W

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kingdoodlesquat - 11 Mar 2007 23:48 GMT

> > Hello all,
> >
[quoted text clipped - 25 lines]
> --
> -Fred W

Cheers Fred. Looks like I'll be forking out for a new sensor then - unless I
can blame it on the crap fuel at Tesco's.

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Fred W - 11 Mar 2007 23:53 GMT

>>>Hello all,
>>>
[quoted text clipped - 37 lines]
> Cheers Fred. Looks like I'll be forking out for a new sensor then - unless I
> can blame it on the crap fuel at Tesco's.

I assume that you already tried changuing the fuse and it blew again?
If so, you may want to just check that the short is not elsewhere in the
wiring. If you follow the cable back from the O2 sensor you will come
to a connector. Try unplugging it, then plug in a new fuse and see if
the fuse blows again. If it does the problem is (obviously) not in the
sensor.

While a shorted heater is not impossible, it's not a common failure mode
for the sensors. That and they are pretty dear at ~$100 a pop.

Signature

-Fred W

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kingdoodlesquat - 12 Mar 2007 00:04 GMT

> >>>Hello all,
> >>>
[quoted text clipped - 50 lines]
> --
> -Fred W

I'm in the UK & its night-time at the moment, so I cann't get hold of any
fuses just yet. Nevertheless, I look forward to frustrating myself tomorrow.
Cars - nothing but a black hole in which to pour copious amounts of cash,
but at least my black hole is a Saab!!!

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