P0171 and P0171 error codes

[Robert63]

Hi All my 04 plate 2.2 Zed 4 has developed a P0171 System too Lean Bank1 and P0174 System too lean Bank 2 could these errors possibly be caused by a faulty Disa valve ????

 

[Number5]

They usually appear when there’s a split in the rubber boot that leads from the air filter into the engine.
Its either allowing air in or out (I’m not sure) but when I had it on my 2.5 years ago that’s all it was. Often the split is on the underside and hard to find but it’s usually there somewhere as the rubber perishes


The rubber boot is about £30 and it’s less than an hour to pop a new one on.

 

[Robert63]

Hi Number 5 many thanks for the advice I have replaced the rubber boot for a new one but I still have the error codes.

 

[Smartbear]

What Alan said ^^
The inlet boot runs under vacuum so a leak will allow air to be sucked in, the fact it’s unmetered air (downstream of the maf) causes the lean running codes.
It’s easy to change, just a bit fiddly leaning over & positioning the clips correctly.
Edit, was the hose you replaced the one with the bifurcated finger attached?
Rob

 

[Robert63]

Hi Alan the boot I have replaced is directly after the MAF.

 

[Smartbear]

Hi Alan the boot I have replaced is directly after the MAF.

You need to check this one https://www.ebay.co.uk/itm/174099547753
It’s the small “finger” that often splits.
Rob
Rob

 

[Number5]

Yes. It’s the pipe that Smartbear has highlighted. It often splits in the ribbed sections

 

[ph001]

What was the rubber boot you changed, and was it split? This is the one everyone above is referring to...

 

[Robert63]

Yes thats the one that I have changed along with a complete new crank case ventilation system, new MAF and cam shaft cover gasket . I am at a loss now !!!!!

 

[Smartbear]

Yes thats the one that I have changed along with a complete new crank case ventilation system, new MAF and cam shaft cover gasket . I am at a loss now !!!!!

Check all the ccv pipe work’s secure, a leak here can also cause lean running.
Rob

 

[bigwinn]

if its any help I had the same codes after renewing vanos seals, when I didn't put the oil filler cap back on straight

I know that reflects badly on me as regards technical competency- but it fixed the issue immediately