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P0171 & P0174 OBDII Codes Advice please.

Discuss problems you have had or are having with your Z4
hsyben
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P0171 & P0174 OBDII Codes Advice please.

Post by hsyben » Sat Jan 21, 2023 7:23 pm

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?

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P0171 & P0174 OBDII Codes Advice please.

Post by bigwinn » Sat Jan 21, 2023 7:43 pm

Deffo no holes in your intake elbow

They do hide underneath!
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P0171 & P0174 OBDII Codes Advice please.

Post by enuff_zed » Sat Jan 21, 2023 7:48 pm

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.
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P0171 & P0174 OBDII Codes Advice please.

Post by hsyben » Sat Jan 21, 2023 8:15 pm

Thanks. I'll take another look.

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P0171 & P0174 OBDII Codes Advice please.

Post by hsyben » Wed Feb 22, 2023 8:57 pm

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.

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P0171 & P0174 OBDII Codes Advice please.

Post by enuff_zed » Wed Feb 22, 2023 9:39 pm

hsyben wrote: Wed Feb 22, 2023 8:57 pm 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 😁
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P0171 & P0174 OBDII Codes Advice please.

Post by GJ1 » Thu Feb 23, 2023 12:56 am

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?
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P0171 & P0174 OBDII Codes Advice please.

Post by hsyben » Thu Feb 23, 2023 1:10 am

Air intake manifold boot. It is number 5 on the diag. In mine the correlated pipe developed a hole
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P0171 & P0174 OBDII Codes Advice please.

Post by GJ1 » Thu Feb 23, 2023 1:21 am

Thanks. How did you find the leak?
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P0171 & P0174 OBDII Codes Advice please.

Post by hsyben » Thu Feb 23, 2023 1:37 am

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.

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Post by enuff_zed » Thu Feb 23, 2023 8:39 am

Be aware there are two types of boot depending on whether you have a sound generator or not.
This being on the M54 engine.
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Post by hsyben » Thu Feb 23, 2023 9:59 am

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.

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Post by GJ1 » Thu Feb 23, 2023 10:01 am

hsyben wrote: Thu Feb 23, 2023 1:37 amyou
:thumbsup: will have a look
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P0171 & P0174 OBDII Codes Advice please.

Post by enuff_zed » Thu Feb 23, 2023 10:06 am

GJ1 wrote: Thu Feb 23, 2023 10:01 am
hsyben wrote: Thu Feb 23, 2023 1:37 amyou
:thumbsup: 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
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P0171 & P0174 OBDII Codes Advice please.

Post by GJ1 » Thu Feb 23, 2023 1:42 pm

enuff_zed wrote: Thu Feb 23, 2023 10:06 am
GJ1 wrote: Thu Feb 23, 2023 10:01 am
hsyben wrote: Thu Feb 23, 2023 1:37 amyou
:thumbsup: 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
07 Z4C 3.0si sport sapphire black

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