Can anyone tell me what types of problems i will get if my Lambda sensor fails?

 

More fuel use than normal Probably a bit of dodgy idling & poor off-boost performance.

There's a few more things too, but my memory isn't very good.

 

would it also be called an oxygen sensor? just had a decat downpipe put on and they said they hadn't put he oxygen sensor back in and notice when cold the car doesn;t idle that well but when warm i have no problems.

 

Yes, it would also be called the oxygen sensor.

Is your car a pre MY96 WRX? If so, then the oxygen/lambda sensor is NOT in the downpipe. (It's in the right hand side headers under the engine) The thing in the downpipe is a "Cat on fire" sensor, and does nothing useful now you've decatted the car.

If it's MY97 or later, then I'd consider getting the oxygen sensor replaced. It'll save grief in the long run.

 

its a MY93 WRX, not sure what he meant then cause he said he'd taken it out. Thanks for your help.