Training

[Shannen Durphey]

Yes, and no.  It depends on the ecm's level of "sophistication".  Older
GM ecm's would run with lazy O2 sensors without setting a code.  New
ones, ODBII, are paranoid little boxes that roll out codes like foreign
money.  Poisoned O2, with antifreeze or silicone, poorly grounded
exhaust/sensor, air leaks into the exhaust can all cause problems which
may not set a code. Insufficient sensor temp, aftermarket "universal"
sensors, even removal of the cat can cause some pretty good driveability
bugs.  There are test boxes, I'm thinking of one by Walker, which will
bias the O2 sensor voltage high/low, and has an led bar display to show
what's happening on the signal line.  This might work for you.

Shannen

Geoff & Sue Richards wrote:
> 
> Hi
> In the interests of training I would like opinions from the gurus
> Is it possible to 'set' a fault within an O2 sensor circuit without setting
> a code?
> I would like to make a vehicle run poorly for diagnostic training purposes
> Any help appreciated
> Thanks
> Geoff
> geoffsue at one.net.au