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1999 E46 318i se fault code p0171.

30K views 120 replies 15 participants last post by  VJPo2 
#1 ·
Hi guys,

I thought i would post this to try and help out other people with similar fault.
First off last year I got fault code p0171 with management light on,so i went searching and found egr start fan had exploded,so I changed that,cleared code and it seemed o.k for 2 days but then it came back on:mad
so checked it was the same code,yes it was so went looking again and found the crankcase breather hose had turned into Plasticine,so i changed that cleared codes again spot on the light stayed off,until last week mil back on (same code again) so after more searching and checking of hoses i found the disa valve diaphragm was split (you have to look carefully to see it) through where the bar goes in but it was there,i will try to get some photos on soon.
If this helps just one person its worthwhile.
 
#92 ·
Guys had MAF replaced. Bosch genuine. Car seems smooth and quicker, slight delay in surge of power from previous one but smooth delivery of power, less grunt throughout gears. What can you advise?

Does it need tuning? Reset adaptive?
Why would a new sensor take time on acceleration for power? Or hesistant?

Did 100 miles on M1 last night, at one point foot flat on pedal then took delay before pier surge kicked in? Seems powerful once there but took longer than previous one in getting there

Please help!
 
#98 ·
I'd say you're pretty much sorted. If I'm cruising above 75 I'm lucky to get anywhere near 35mpg, however if I keep it between 65 & 70 I can make 40mpg.
Now that you've solved the 171 fault code problem I'd go with a good service and keep an eye on the fuel consumption.
 
#99 · (Edited)
Thanks, It seems hesitant on power so local garage where had MAF fitted asked me to bring it in to check any leaks etc, also reset adaptive. may help. I dont think it was reset at the time of fitting, as he's brother did it so may not be aware (don't know really) all I can do is ask. He said bring it in and he'll check it out further. worth having a final check then book in for service at time its needed to be. think air filter will make a change?

Its strange I used to idle funny but gave more MPG before new MAF. I would have thought its the other way around?

Update; Later this eve noticed a little hissing in 4th and 5th only after 4k rev's!
 
#100 ·
If your hearing hissing in 5th over 4k rpm it's probably the wind as your doing about 85! A new air filter will make a huge difference. Do the service yourself, get a K&N panel filter aaaaand, you'll save a load of money and get to know your car a bit better, the M43 is such an easy engine to work on. Buy a Haynes manual and get on with it.

Interested to see if your engine light stays off and the MAF sensor option from ECP is a way better option.

C.
 
#103 ·
As I said I sorted this with a second hand Bosch mad and new panel filter what a difference car still feeling like a rocket I needed had the engine light switched off that was it I'm no car man but sounds like a dodgy maf or u have more issues
Cheers, Something does not sound right. Prob faulty MAF or leak, since the light has been off over 250 miles (Mixed roads) hissing is at 4-5k RPM in 4th and 5th. Not heard that prior to change.
 
#104 ·
Ha... Was just checking back through the content of this thread and found that VJPo2 didn't even start the topic! Awesome, good advice in here though, even if a bit long winded.

No new update from me but I'm still trying to work out where a wierd noise comes from on start up, is does sound like an air pump doesn't sound like where the pump is situated. I don't think this has much to do with my 171 fault code.
 
#106 ·
The noise will more than likely be the air pump if it is just on start up from cold, the rivets get loose and let air out, take the rivets out and replace them with bolts or tie wraps, you can test this by opening your bonnet when you start the car, when the air pump starts push down on the lid firmly and see if it gets quieter
 
#110 ·
Guys

Please help, same code P0171 after replacing MAF with Bosch.

Symptoms are the following prior to light displayed
Surges prior to fault light coming on (take 2 days of things before brings up fault light)
Air vents motor noises, like clicking sound Cricket like, water sound effect from inside the air vent (this continues when light off or on) Think it just adjusting itself

Can you help me identify the issue please, I am at the end of my tether after spending money on things that might not have been needed.

Please help if anyone has heard of these symptoms to help diagnose the issue.

I look forward to hearing from you.
 
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