Lagging in power

Hi Guys, my first time in the forum.
I have a power lag on my citroen c3 attaraction, 2011 petrol model. (about 82000km on the clock)
I took it for a major service in November last year and ever since I had a lag.
They "replaced" the spark plugs and the cambelt was done too 'cause it had little cracks in - ever since I have had a noticible lag in power.
1st,2nd and 3rd gear was great 4th and 5th lags so much so that I can only do about 80km/h on the freeway (uphill)!!
The engine check light came on and the diagnostic machine gave the code for the Bank 1 senson 2 oxygen sensor "stuck"
I bought one and replace it now the heavy petrol smell is gone but the lag persists, eversince i did this the "power" it had in 1st and 2nd is down but it feels much smoother on pull away and do about 90km/h now on the freeway (uphill) but if im not on speed I have to gear back when its an uphill to 2nd or even 1st - which it never used to do I could do that same hill prior to the service in 4th and maybe gear down to 3rd.
I have seen another post on the forum how to clean the accellerator sensor (fly-by-wire sensor) and will that this weekend - but I cant understand the sudden lose in power could something else maybe be wrong?
sometimes the engine check light still comes on but still only shows the lean bank 1 sensor 2 oxygen sensor as stuck, then I just clear the fault - I do not have that potent petrol smell anymore so the sensor must be working.
Any other help would be appreciated if the accellerator sensor is not the culprit.

Thanks
Matty

Hi Mad Matty

As this all started when you had the car serviced did you go back to the garage that did the work?

My feeling is that they either fitted a wrong part(s) or didn't fit something correctly. I think it's worth spending a little time going over what they did.

Your sensor issue could be connected but from what you're saying I think maybe not.

I'm even thinking could the garage have got the timing out when they replaced the cambelt?

Thanks that was an initial thought by me too. I did however find that spark plug 2 was never put in tightly and also checked the other spark plugs and put them back the car runs a bit better too after that but should i consider checking the accelleration sensor before checking out the cambelt timing? What would you suggest?

Oh one thing i also forgot to mention is when i depress the accellerator there is a 1 to 2 second delayed response in the car accellerating. While normally when i used to put my foot on the pedal it would instantly respond.
Thanks for your advise this site is a great site!!

Mad Matty wrote:Thanks that was an initial thought by me too. I did however find that spark plug 2 was never put in tightly and also checked the other spark plugs and put them back the car runs a bit better too after that but should i consider checking the accelleration sensor before checking out the cambelt timing? What would you suggest?

I would do as Missing Lincs suggested and that is go over the work that was done by the garage. The reasoning is as was suggested,

Missing Lincs wrote:My feeling is that they either fitted a wrong part(s) or didn't fit something correctly. I think it's worth spending a little time going over what they did.

Which makes more sense as a first step than anything unconnected to what was done when the fault appeared.

Mad Matty wrote:sometimes the engine check light still comes on but still only shows the lean bank 1 sensor 2 oxygen sensor as stuck, then I just clear the fault - I do not have that potent petrol smell anymore so the sensor must be working.

I would disagree with your assumption. If the ECU detects a O2 fault, then there is a problem with the fuelling or the fuel burning. The O2 codes don't always mean the sensor is faulty, but the sensor has detected a fault condition.

You can buy a OBD2 reader quite cheaply and probably less than the cost of one 'read' of diagnostics at a garage Here - ebay which will prove to be useful for getting the 'P' codes.

Mad Matty wrote:The engine check light came on and the diagnostic machine gave the code for the Bank 1 senson 2 oxygen sensor "stuck"

Did you get the 'P' code for this from the diagnostic machine?

Hi Guys

Yes I have a diagnostics machine and it gives the P2207 code I think it was - but it also gives what the code is, which is "LEAN BANK 1 SENSOR 2 STUCK" (it also reads bank 1 sensor 2 oxygen sensor in the anual for the code given)
And that is the only code it reads when my check engine light comes on - there are no other error codes it detects.
Should I maybe also check the fuel pump or fuel filter ? (which I feel should actually have been checked in the major service but was not replaced - unless it was checked and did not need replacing - as the air filter was replaced though)
But yeah I will check the accelarator sensor and take the car to be checked out for the timimg as I am a bit scared to fiddle on the cambelt myself