Eobd fault codes - Alfa Romeo Forum
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(Post Link) post #1 of 2 Old 21-12-11 Thread Starter
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Eobd fault codes

156 SW 2.5 V6 2001; engine AR32405 / 932B1100

We've got the following fault codes - P1172 and P1175. The definition source my man uses says no data from manufacturer

Can anyone help?
rachelfretwell is offline  
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P1172 Lambda adaptat. 2 (additive) above upper limit
P1172 Lambda adaptat. 2 (additive) below lower limit

Assuming the lambda sensors are in good working order the usual causes are:

Defective MAF, indicated by well into the negative Long Term Fuel Trims...

Unplug the MAF take it for a run and see if the engine is pulling better in the upper rev range....It will hunt for revs on idle or even stall while it is unplugged, that's normal.... Oh and the yellow warning light will come on the dash, it will go out once re-plugged back inIf it does pull better then the MAF is faulty...
Try doing a search for "how to clean the MAF" first before actually replacing it, it could save you 's

Air leak after the MAF in the convoluted flexible intake hose; check for cracks in the flexible hose.

Take off the rubber air induction hose and seal the ends with elastic bands and rubber gloves.... Place it in a bowl water to check for leaks... air bubbles will come up if there are any.
A cheap "pound shop" bicycle inner tube repair kit is all you need!... The glue(vulcanising fluid) can be rubbed in between the split and sealed, in 15 minutes it will be stronger than it was before and air tight... saving 's on a new convoluted air induction hose! Which is an Alfa only part

Blowing exhaust between the exhaust manifold and the lambda sensor. Check by holding a cloth or thick glove over the exhaust tip to create back pressure... any cracks or holes will sound like a louder hiss coming from further up the exhaust/ manifold... Many independant tyre and exhaust centres offer free exhaust checks... let them find out exactly where the leak is, if there is one!
Then simply get a friendly mechanic to weld up the offending area if it isn't too bad, saving 's

P1175 -Cam control fault/mixture 2 strength : Related to common possible causes above

My educated guess would be a leak in the rubber air induction pipe creating both faults Weak air mixture that is making the lambda read out of its given value.

Last edited by Grahameo; 21-12-11 at 12:45.

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codes , eobd , fault

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