Question about 1999 BMW 318 ti

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Bmw E46 318i touring. fail code 171

I took my bmw to the deelers and they diagnosed the car as having a faulty mass airflow sensor. i have replaced the sensor and now i have a code of 121. this second code occures after only 35 miles each time i cancel code, but before i replaced the mass airflow sensor it would ocure after about 100 miles each time i canceled it. have i done something wrong when inserting the new mass air flow sensor?

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  • nikgha Apr 02, 2009

    my car have problem fail code 171/P0170,Change everything including valve fuel filter,fuel pump and check all intake no leak but after reset the fail code the problem still same engine light on. please help.



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171 check, fuel supply system short circuit to b+

Posted on Jul 11, 2009


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Codes 174 171

Fuel system too lean.

PCM software needs to be updated

Vacuum leaks (Intake Manifold Gaskets, vacuum hoses, PCV hoses, etc.)

Mass Airflow Sensor (MAF)

Plugged Fuel Filter or weak Fuel Pump

Plugged or dirty Fuel Injectors

Common Misdiagnosis would be a faulty o2 sensor

Sep 20, 2014 | 2005 Suzuki Verona EX

1 Answer

WHAT IF TwO CODES COME UP 0171 and 0174?

I doubt it.
If the MAF sensor was faulty you should have a code for it too.
The most common cause for code 171 and 174 fuel mixture too lean is low fuel pressure.

Sep 01, 2014 | Cars & Trucks

1 Answer

I have a99 BMW 528i 6 cyl. It Wil not throttle up. Only about 2000 rpm and idles a little rough , what do think.

First two most likely suspects: 1) A big crack in the air tube that runs from the air filter to the throttle body. 2) A failed mass airflow sensor.
You should get a check engine light which will store a trouble code. However, there is no trouble code for "massive air leak in the intake tube", so if that tube has cracked, the code will point to some related sensor or system.

May 08, 2011 | 1999 BMW 5 Series

1 Answer

97 bmw 318ti mass airflow sensor diagnose code P1140 comes when starting the car i replaced maf problem still exists checked hoses all okay,

The p1140/121 code indicates the MAF was not as expected compared with values from IAT, TPS, CTS, IAC command, and RPM. Meaning all THOSE sensors and the IAC solenoid position data have to be working and in normal range for the MAF to test normal and not code. Further, any vacuum leaks will ruin the MAFs accuracy when compared to the others, as will a PCV/CCV problem.
If you lobbed a MAF at it have already done the least likely and most expensive part. You really need to look at data and see what the DME sees. Is throttle showing closed at idle, is air temp normal? Is RPM under 725 idling, does it flare idle up and down in 10 seconds. is there any vacuum leakage anywhere? even a small amount can make a code level of difference?. Intakes leak a fair amount. CCV valves much more likely to leak, as are the hoses to it. TPSs dont fail that often but can. IACs usually code when they fail...but they could plug up and not code but have improper air bypass that affects the MAF reading. Throttle cables/adjustment is critical...keep that high on priority list.
iATN Tech.

Jan 16, 2011 | 1997 BMW 318

1 Answer

Hi, i have a 1999 bmw 323i and the is not giving me the performance as usual, it wont pick up speed fast, if am going 50mh and i press the break and than press on the gas it wont respond fast at all even...

A few classic possibilities here. First your throttle body sensor may be bad. Second your mass airflow sensor may be bad. Third your fuel regulator may be on the blitz. Also, if your oxygen sensor is going bad you may feel a slow response to your acceleration. My best bet is that your mass airflow sensor is going bad. Please have your car diagnosed at the nearest AutoZone for free.

Oct 18, 2010 | BMW 323 Cars & Trucks

1 Answer

I have replaced the port seals, isolater bolts, cleaned the EGR ports, plugs and wires, and chanced the air filter. I was getting both 171 and 174 codes. Now after 60 miles or so, pulled the codes again...

P0171 is a lean fuel condition . The computer reflashed has nothing to do with it . Vacuum leak intake manifold probably . If both P0171 & P0174 were back could be fuel pump low flow or restricted fuel filter . or O2 sensor problem or mass airflow sensor. Suggest you take it to a qualified repair shop to have it diagnosed .
Ford 150 P0171 P0174 Trouble Codes vacuum leak water test

Diagnosing Faulty Mass Air Flow Sensor P0171 P0174 Lean Codes

Aug 10, 2017 | 2000 Ford Windstar

3 Answers


i have a 2001 bmw 330i and i want to know were is de 02 sensor bank 2 , sensor #1

Jul 07, 2010 | 2001 BMW 3 Series

1 Answer

Code 29 ( Air Mass Sensor ) on 93 BMW 525I What this mean

It means your Mass Airflow Sensor (MAF) is bad, test and replace if necessary.

Jun 24, 2010 | 1993 BMW 5 Series

2 Answers

Can I repair airflow meter instead of replacing it

nope - if air mass is faulty then bes buy a new one ... or a tested 2nd hand one

Jan 13, 2010 | 2002 BMW 5 Series

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