Psss noise from engine bay

[GJ1]

Hi all, after any available advice although might be difficult to identify the issue...

I had an oxygen sensor replaced today (and MOT) and when I returned home and turned the ignition off the yellow oil light came on very briefly. When I switched the ignition back on the warning light didn't come on. I checked the oil guage thingy and it said OK.

Then when I got out of the car I heard an intermittent (every 3-5 seconds) 'psss' type noise coming from the engine area. It was dark and couldn't really identify exactly where it was coming thought but perhaps from under the engine cover.

So my questions are:

1. Do you think it is likely to be related to having the oxygen sensor replaced or coincidental?

2. How do I go about identifying the likely cause? At the moment I am wondering whether a hose might be loose, oil or gas is leaking from somewhere, or maybe liquid is dripping on hot engine/pipes somewhere making the noise. It was raining heavily on the drive home. Unfortunately I'm not that handy myself but would like to attempt to identify the issue if at all possible before taking it to a garage for, most likely costly, investigations.

Thanks

 

[rdm05z4]

Was it doing it before the sensor was replaced? I would first do a few things start the car get to temp then with bonnet open listen for sound when car turned off. If doesn't happen, then possible a drive then repeat process bonnet open listen. If still hearing and can't find the source then would take it back to shop that replaced the sensor (if noise was no present prior to new sensor). Possible they just knocked off a hose.

 

[GJ1]

Was it doing it before the sensor was replaced? I would first do a few things start the car get to temp then with bonnet open listen for sound when car turned off. If doesn't happen, then possible a drive then repeat process bonnet open listen. If still hearing and can't find the source then would take it back to shop that replaced the sensor (if noise was no present prior to new sensor). Possible they just knocked off a hose.

Thanks. Sound advice, will try that.

I've not noticed a noise before but can't say with absolute certainty it hasn't been there before although if it was I think I would have heard it like this time.