w209 system too lean P0171

[coupefan]

Hi all...experienced advice required again. Car running well and I get the engine warning light. Bought a code reader and it comes up P0171 system too lean, bank 1.
Could this just be poor quality fuel as I filled up at a different garage?
Is there anything I can check for leaks or clean? I did have a small oil leak a long time ago from the oil filler cap...now sorted?
The little code reader could not clear the engine light.

Any ideas gratefully received ! Thank you.

 

[mercedes13156]

Until you get it on a decent diagnostic machine and eliminate things one by one, we'd all just be guessing, as I am.

It might even be something as simple as a badly clogged air filter.

 

[coupefan]

diagnostic

yes, I am trying to save money as always! Trying to avoid another garage visit...had a few too many of those this year ;-)

 

[LostKiwi]

Check for vacuum leaks around the throttle body maybe? How is it idling?

 

[coupefan]

Thanks...I will try that...seemed to be running very, very well last time I drove it...will see how it idles from cold....

 

[umblecumbuz]

I would not have thought the fuel you recently purchased is the reason for this code.

As you say that the engine is running well, it suggests your code is an uncleared historic one. Often an engine idling erratically will throw such a code, and this sometimes indicates an inlet manifold leak, or even too much fuel - in other words, an air/fuel inbalance.

Clear the code first (many good code readers will do this without hassle) and then see if it returns.

Umble.

 

[coupefan]

Thanks Umble....that's what I was hoping to do...the code reader (bought from Ebay!) is supposed to read and erase codes but so far I can't get it to clear. Will have another try tomorrow.

 

[coupefan]

could it be an airlock....not putting the fuel cap on tight enough maybe? We had a big change in temperature on that day.....

 

[mercedes13156]

could it be an airlock....not putting the fuel cap on tight enough maybe? We had a big change in temperature on that day.....

Probably not!

 

[Uncle Benz]

There is a breather hose under the air filter box that often splits and gives that code. Have a listen for hissing under there. A bit of hose in the ear helps.

 

[Steve@Avantgarde]

Sounds like it has an air leak and the mixture is wrong.

 

[coupefan]

Idle is fine...steady at 700rpm...running well..mpg good...today the engine light went off again...weird one...

 

[mercedes13156]

yes, I am trying to save money as always! Trying to avoid another garage visit...had a few too many of those this year ;-)

Buy a decent scanner like one of the iCarsoft ones and you'll be able to save yourself a good bit of money by not having to visit the garage so often. You'll find that if the scanner doesn't tell you exactly what's wrong, by telling us what the codes are, we can help diagnose and suggest things that could be wrong as well as providing nut and bolt instructions on how to fix it yourself.

Spend a bit to save in the long run. Soon you'll be chipping in to provide help to others.

 

[LostKiwi]

Buy a decent scanner like one of the iCarsoft ones and you'll be able to save yourself a good bit of money by not having to visit the garage so often. You'll find that if the scanner doesn't tell you exactly what's wrong, by telling us what the codes are, we can help diagnose and suggest things that could be wrong as well as providing nut and bolt instructions on how to fix it yourself.

Spend a bit to save in the long run. Soon you'll be chipping in to provide help to others.

He has a code reader (mentioned in post #1). No idea which one but he does have one.

 

[MercSLK]

Hi Coupefan

PM sent. Answering by PM these days as being pursued by 'keyboard warrior' and can't be bothered getting into pi**ing contests.

HTH

mercSLK

 

[coupefan]

Yes, the light is off now...I think it was something to do with that last fill up...the filler cap was not fully on... air bubble...incorrect mixture...let's hope it's a blip as it's lovely to drive!