malfunction fuel trim bank 1 ???? help please
 

i had my mate do a diagnostic on my 2001 4.4 e53 after the trio of lights came on which turns out to be the rear abs sensor.
also "malfunction fuel trim bank 1" came up.
what is this please. what should i check and how do i fix it etc.
thanks.

p.s. i only fitted the rear speed / abs sensor 6 mths ago. i should have got an oem one

buy cheap, buy twice.

If the trouble codes have not been cleared the fuel trim code could be an old code and no longer an issue. Do you have any symptoms there is a problem?

It does seem to accelerate a bit juddery.

"does seem to" doesn't sound like you are sure there are symptoms. If that is the case, unless you are sure the code is new, I would clear it and see if it comes back in a day or two.

If there are clear symptoms, I would check for an obvious vacuum leak. Finding none, I would check connection on the pre cat O2 sensor on that bank. If it seems to be OK I would clean the MAF with MAF cleaner, usually helps enough that the problem is pinpointed. If the problem is not resolved I would swap O2 sensors side to side and see if he code moves to the other bank and go from there.

Whenever there is a miss or feels like there is a loss of power I gravitate to the MAF and clean it as the odds are good that is the problem, easy to do and can't hurt if you use MAF cleaner.

it is a bit lumpy on acceleration.
also what is a maf and how do i clean one?

Oh brother!!!!!!

There's plenty of videos on youtube about MAF and how to clean them. If you decide to replace the MAF, don't buy a wing wang or wing wong MAF from eBay or Amazon. Buy a genuine Siemens MAF.

I have attached a youtube video that explains what a MAF does and how to clean it. The MAF in your 4.4 looks quite different but the only wires coming out of the air intake tube are for the MAF.

https://www.youtube.com/watch?v=gRfaPfTcfOM