Polo 1.0 MY2000 P0171 code

[Luxobarge]

Hi,

My son's manual Polo 1.0 (MY2000) just put the EML on yesterday, under normal driving conditions, just as he was coming to a normal halt.

I read the codes (I have a scanner) and it's thrown a P0171 - System too lean, Bank 1

I've read up on what this code means, but I'm asking on here if there are any common causes of this fault on this model?

I'm suspecting a vacuum leak somewhere, and I will go and have a look when I have some time in the daylight (and when the lad has the car here!) but I'd be grateful if you could tell me if there are any common places for a vac leak to occur, or if you have a vacuum system diagram you could post up?

The car runs pretty much fine otherwise, although he has reported occasional jerkiness in the engine, I'd always put it down to his driving though....

The car has done 89,000 by the way, has FSH and is an absolute beauty, we love it. The only work I've had to do was slap a cam belt and tensioner on it about 1000 miles ago, as there was no evidence of it being done before.

Many thanks - much appreciated!

Cheers

[Guest 2]

Rosstech give you a list of things to check - 16555/P0171/000369 - Ross-Tech Wiki

Welcome to VWAF

[Luxobarge]

Rosstech give you a list of things to check - 16555/P0171/000369 - Ross-Tech Wiki

Welcome to VWAF

Thanks Chris - yeah, like I say I've read up on the code, and I know all that stuff, I was just after people's knowledge of this model, if there were any model-specific areas or weak points to look at that might be "favourite" to cause this.

Cheers!

[Luxobarge]

Nothing?

[Sam]

As Chris has said, Ross Tech have it pretty much covered, I presume you've read their Fuel Trim Info page and followed the suggestions therein?

After checking all hoses for leaks, the next step would be a new, genuine MAF.

[Luxobarge]

As Chris has said, Ross Tech have it pretty much covered, I presume you've read their Fuel Trim Info page and followed the suggestions therein?

After checking all hoses for leaks, the next step would be a new, genuine MAF.

Many thanks. Yes, I've read all there is to read on the subject, but so far it's all been "generic" stuff. So, your steer is vac leaks followed by MAF - sounds sensible. I haven't had daylight time to start poking around yet, but certainly will do.

a) Anywhere you'd recommend getting a "genuine" MAF - apart form the VW main dealer? Is it a bosch system?
b) I don't suppose anyone has a vacuum diagram for this engine they could post up? Always easier when you can see what pipe does what, and goes where!

Cheers

[Sam]

It's generic stuff because the fault covers a lot of engines.

Start with the vacuum lines, yup. Mine cracked at the elbow downstream of the MAF over the back of the engine bay, but I have a Passat and a longitudinal engine.

1) TPS or a dealership for the MAF, just tell them your reg and VIN and you'll get the correct part. Dealerships will sell you the MAF at a reduced rate if you part-ex your current one or you can pay full price (and weep like a child).

2) Easiest thing you can do is go to vagcat.com/epc/, sign up to their forums to get full access to the diagrams and part numbers and then hunt for your exact model - if you can't be bothered to sign up let me know the engine code and I'll see what I can do.

[Doctle Odd]

There's not many pipes on these engines 5 minutes would check them all

[Luxobarge]

Excellent, thanks chaps, some useful info there. Still haven't had a chance to look at it yet, as it's my son's car and he's away out and using it. Looks like it'll be a boxing day job.... Still, it hasn't put the light back on since clearing it after the first code, so can't be too serious, here's hoping it's just a nice simple (and cheap!) vac leak. I've had the top engine cover/air cleaner off a couple of times, so I probably disturbed something there.

Cheers!

[Luxobarge]

OK, so if anyone's interested, I've fixed this. Pulled the air box off and there was a small vac pipe down the right hand side (passenger's side) that was not connected - I think I probably pulled it off last time I had the air box off and failed to re-connect it properly. The car is running much better now, less hesitant, smoother and more responsive etc. and of course no return of the error code. A nice cheap fix and a lesson to be more careful in ensuring that everything is re-conencted properly whenever I disturb the air box.

Thanks for your help on this. I'll probably be back next time something goes wrong....

Cheers!