Is this a MAF fault?

[copestake]

Hi, on my girlfriends car (Toyota Yaris 1.3) the engine management light comes on about about 20 miles. Fault code P0171, engine running lean.

I've checked the live data and for the airflow it never goes about 0.10lb/s on wide open throttle. I assumed the MAF was faulty so replaced with another from a breakers but still have the same. I know there is a possibility that one is faulty to but would just want to double check i'm not missing something?

I've checked all the hoses & there's no sign of any vacuum leak. No rough idling and still drives fine.

Thanks

[pringle1988]

Was going to say vacuum leak, you can spray something like wd40 (probably something better than this) onto a suspect hole on a hose or joint and listen for the engine idle to change.

Have you tried cleaning the MAF sensor? Also I know on my car a common fault is the wiring breaking down leading to the MAF sensor, this could be worth a quick check. Also im sure ive heard of O2 sensors causing similar problems although I think these have a seperate code for themselves.

Sorry im not much help just thought id throw some suggestions in.

[copestake]

pringle1988 said:

Was going to say vacuum leak, you can spray something like wd40 (probably something better than this) onto a suspect hole on a hose or joint and listen for the engine idle to change.

Have you tried cleaning the MAF sensor? Also I know on my car a common fault is the wiring breaking down leading to the MAF sensor, this could be worth a quick check. Also im sure ive heard of O2 sensors causing similar problems although I think these have a seperate code for themselves.

Sorry im not much help just thought id throw some suggestions in.

Thanks for the reply. I had the whole intake off yesterday to try and find a leak but couldn't find a thing. I tried a different code reader that measured the airflow in g/s and seemed to be operating fine.

Anyway it's all back together and the engine light hasn't shown up yet so fingers crossed but that is a good idea to check the wiring. Will be my next step. Thanks