Fault code P1128- 'Long Term Fuel Trim - System Too Lean Bank 1

[bassat]

Hi,

i have a 2001 Passat 1.8T 20v Sport & have had the P1128 fault code for quite a while. I tried various fixes; every pipe linked to 'bank 1' has been checked / replaced but it doesn't seem to get rid of the fault code.

I've recently discovered it could be a faulty MAF sensor but wanted to check that the symptoms are consistent with this kind of fault.

Initially there were no symptoms when the light first came on but gradually the car has been idling poorly, misfiring, very jumpy whilst the engine is cold & there is a distinct loss of power even when the engine has been going for hours - even on motorways. The car also failed it's MOT due to high emissions.

Could all of this be due to the MAF sensor or are there other things I should be checking?

Any feedback would be much appreciated.

Many thanks

[bassat]

bump...please help!

[Kicha_1981]

Hi,

I am also having similar issues. I tried in other VW forums and seems most likely a faulty MAF sensor. I am taking my car to the dealer tomorrow. By the way, Did you have any luck in fixing this? If so , pls let me know what the issue was.

Thanks in advance

Krish

[bassat]

Hi

Yes I fixed it & it was definitely the MAF sensor. I bought the sensor (Bosche) for around £65 from German & Swedish (costs same in Euro carparts). There's a £25 surcharge which they refund after you return the old sensor. Cost me £20 labour from a regular mechanic to fit. Drives like brand new now.

If you hadn't already booked in to a dealer I would have advised against it. They'll charge £94 just to diagnose & then probably another £200 to do the job. Have you already checked to the fault code & found it to be P1128? If so then 90% chances its your MAF in which case do what I did & save yourself from getting ripped off by VW.