P0171 & P0174 OBDII Codes Advice please.

[hsyben]

The dreaded 'Check Engine' light came on part way through a journey in my 2003 E85 2.5i Z4. My OBDII reader tells me that it is System Too lean (Bank 1 and 2) and the web says it might be an air leak in a boot or pipe or a faulty Oxygen sensor.
I cancelled the light but it came back 30 mins into another journey.

The boots and pipes look to be in good nick and I'm wondering why the fault would only display after 30 mins drive time?

Is this something I should book into a garage to fix or can I keep driving the car? Could it be the sensors - I saw a thread that they can fail after 60,000 miles and mine is on 84,000?

 

[bigwinn]

Deffo no holes in your intake elbow

They do hide underneath!

 

[enuff_zed]

I'd check that elbow again, as bigwinn says. It's the concertina type small hose that cracks.
A simple job to change and they can be picked up around £32 from BMW dealers on eBay.
If the pipe is letting in air that the MAF doesn't know about then the engine sees it being too lean and keeps throwing in more fuel until eventually the mixture is so rich it overwhelms the sensors. Resetting it possibly takes it back to a default setting and it takes 30 minutes to do it again.
Also check the hoses and inlet pipes are actually fitted correctly.

 

[hsyben]

Thanks. I'll take another look.

 

[hsyben]

Found the leak - my garage missed it! It was the elbow so getting a new one and I'll fit it myself. Thanks for all the advice.

 

[enuff_zed]

Found the leak - my garage missed it! It was the elbow so getting a new one and I'll fit it myself. Thanks for all the advice.

Ignore the garage.
Trust the forum

 

[GJ1]

As someone that may have a similar issue can I ask what the boot and elbow mentioned above are? Also is it easy to explain, or better still highlight on a photo, which hoses/pipes might be worth checking?

 

[hsyben]

Air intake manifold boot. It is number 5 on the diag. In mine the correlated pipe developed a hole

 

[GJ1]

Thanks. How did you find the leak?

 

[hsyben]

On mine there were obvious holes in the corrugated pipe. Worth giving it a good look on top and underneath. But, if you have these fault codes, maybe change the boot anyway? At £30 you don't have much to lose and you can diy it with just a screwdriver.

 

[enuff_zed]

Be aware there are two types of boot depending on whether you have a sound generator or not.
This being on the M54 engine.

 

[hsyben]

Ah, thanks for that. I ordered mine from the BMW dealer and they asked me for the reg. I'm hopeful that they will have got the right one but I'm off to look at the existing boot more closely.

 

[GJ1]

you

will have a look

 

[enuff_zed]

you

will have a look

I note you appear to have an N52 engine. My advice was based on knowledge of the M54 so don’t let me mislead you. Worth a check though

 

[GJ1]

you

will have a look

I note you appear to have an N52 engine. My advice was based on knowledge of the M54 so don’t let me mislead you. Worth a check though

Thanks for the heads up

 

[hsyben]

Changed the boot today. Not very hard, just a bit of jiggling. Seems to have done the job. Thanks for the advice folks