System too lean banks 1 and 2

[Little Lady Katie]

Oops so I did have another query I wanted to put to the group

A couple of weeks ago, my engine management light came on. I thought to myself 'ut oh! That's not a good light to have on'

I've got a good code reader and ran the codes and it came up with the system too lean bank 1 and 2 codes (p0171 and p0174)

The engine is running beautifully and I've noticed no change. I'm wondering if it might just be an O2 sensor or the MAF sensor?

I have an aftermarket exhaust - I had a stainless steel exhaust system made for my felix from the engine manifold right through to tailpipes 2 years ago now with 2 sports cats built into the system. I don't know if this would/could have any bearing on it (the cats specifically I guess)

I'm wondering where to go from here - is there a way to find out exactly what part is playing up (e.g. An O2 sensor, a MAF sensor, or could it simply be a bit of perished rubber hose?) . I'm worried iim going to end up guessing and replace costly parts that I don't need to one by one in order to try find out where the fault is

Thank you in advance my lovely fellow zed heads!

Katie x

 

[EnthuZiaZT]

Have you checked the air hoses for splits or cracks?

Mike

 

[Little Lady Katie]

Hi mike! Thanks for your reply. No I haven't! These are exactly the kinds of suggestions I need because, although I like to think I know more than the most female about my car, I am in no way close to mechanic-level knowledge or understanding!

this is going on my to check list, and I'll report back with updates to let you know how I get on!

 

[Redline]

As Mike suggested, check for leaky pipes first. Most likely culprit as the material perishes over time.

 

[billz]

Check the little hose that runs from the back of the Maff. Ours went on the Z3 and said the same as yours. they tend to crack on the underside of the hose

 

[Grumps]

Yep agree with the above. Mine has just split causing the car to stall all the time. £13 delivered of eBay. Also possibly the lambda sensors. See if you could get your local garage to pop a probe in the exhaust to check if the emissions are up.

 

[Aceman]

I seem to remember Katie that you said you had replaced this rubber boot/tube when we met last year however I remember at the time when I inspected it for you thinking that doesn't look as though it has been replaced recently so I would certainly check anyway. I do remember giving the other smaller tubes a quick check at the time but one of them could have split in the 12 months since then.