OK, so here’s the first issue with our newly-acquired Citigo SE 60PS (2015).

 

After a 50 minute drive at motorway speeds, sat idling in a car park the CEL came one. No other symptoms and it still runs. Before this I had noticed a slight hesitancy or fluffiness at light throttle and slow engine speeds.

 

I assume I’ll need a OBD device of some kind to interrogate the ECU?  Is there are reset capability for the ECU, like pull this fuse, pump the brakes 5 times and touch your nose with your tongue?

Check for fault codes, for misfires, but maybe not logged if not enough in a cycle.

Maybe replace spark plug time.  Look in at the airfilter and see condition of that.

?

Is there a recent service history?

Yeah, it has a full Škoda history, including spark plugs not that long ago. I’ve ordered an OBDEleven to see what this turns up. Maybe it’s a lambda sensor - it drove home OK, albeit with the slight stumble at light throttle.

OK, so the OBDEleven tells me fault P2096 - "Post Catalyst Fuel Trim Too Lean".  Probably the lambda sensor.  I've cleared the fault and will see if it comes back.

Did the fault come back? My Citigo has just shown up the same fault.

16 hours ago, GoldyJ said:

Did the fault come back? My Citigo has just shown up the same fault.

It did a few days ago. It has thrown two codes related to the post-cat lambda sensor. I’m having it looked at tomorrow.

 

Fuel economy has also gone through the floor and it smells rich when idling.

make sure any new sensor is the correct VAG-supplied part - there are a lot claiming to be compatible but which are not.  This comes up regularly on the Up! forum.

 

appearing to be running too lean (which will cause the system to up the fuelling supply) might be a real fault - an air leak, an injector clogging up, and other things could cause this.

Well the garage agreed with me and fitted a new lambda sensor. All sorted now!  It’s nice to drive again.  I’ll get it serviced next month so will get fresh oil and spark plugs.

So, after replacing the lambda sensor another error popped up within a day - this time related to the heating circuit in the same lambda sensor.  I took it back and they claimed to have "rewired it" and reset the code.  The error came back the same day so I took it back AGAIN.  This time they ordered and fitted an OEM sensor (rather than the aftermarket one they had used) and since then it has all been OK.

Common problem - not all lambda sensors claiming to be compatible actually are, and it's often the heating circuit calibration; this is one thing that may be worth buying from a VW dealership garage, unless you are very sure that it's known to be identical. Many garages have not learned this yet and just buy from a favoured parts supplier, usually based on price....