Need help with my car! P017100

[Rekant]

So ive bought a seat ibiza 1.2 petrol (non TSI) and ever since, the car was running extremely rough on idle. So i had it diagnosed and it was a O2 Sensor (bank 1 sensor 1), so i had that changed with one from the scrapyard (in good condition). Now the cars been fine for a week and now the engine lights come on so i had it re-diagnosed and now its coming up with Fuel Trim Bank 1-System too lean and honestly it could be so many different things i cant be bothered with this anymore, anybody got any help or advice? Many thanks

 

[Crossthreaded]

Fuel filter? people often ignore them. Pressure regulator? Inlet gasket air leak? - just to start you off. Anyone know if there's a common culprit?

 

[RUM4MO]

It might seem strange that this issue only appeared after the faulty Lambda sensor was changed for a used one, but there again, the B1 S1 sensor is a regulator for the injection system, so is it, while still working in some sort of way, causing the base part of the injection timing to be forcing an over rich mixing?
Can't be many people paying a bit of money for a used Lambda sensor I'd think.

Edit:- that was a suggestion, that is all.

 

[Crossthreaded]

I'm still a bit "rusty" with diagnostics but does it run equally rough when cold before it heats up enough to start using the Sensor output (ie closed loop) if you just pulled the O2 sensor plug when hot it would revert to running on the stored fueling program like when it's cold wouldn't it? So if it's an O2 sensor problem you'd expect pulling the sensor wire to make a noticeable difference and probably better/smoother running? Of course it would post a code but that could simply be wiped when you'd finished.

Personally I'd never buy a used oxygen sensor. In fact I wouldn't even buy a new universal type one. O/E from a big name manufacturer, preferably same manufacturer and part number as was fitted at the factory. As RUM suggests above, it may well be this "unknown" factor of a used component which is causing problems. The few O2 sensors I've "investigated" have affected mid range running and caused hesitation when calling for power, these engines ran well at tickover. I'm not saying it's not that the sensor may have a fault (you really need to graph it's output) but maybe something else is more dominant?
This might help? https://www.samarins.com/diagnose/p...II trouble code P0171,air and too little fuel.