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Old 03-02-2017, 10:44 AM   #1
Giode
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Join Date: Jan 2017
Location: 97408
Posts: 3
My Ride: 2001BMW325Ci
Mass Airflow sensor

Hey folks!

I'm Gio! I joined some months ago before getting my BMW 325ci Vert 2001 80k (black sapphire metallic)It was an old family car that was not being driven and sitting in the Florida Sunshine for 2 years.

Anyways, I have had the SES light on since it's arrived to me in Oregon. After much research on this great site and going over all the suggestions for SES. I avoided the hefty dealer fees in checking the code and went to Autozone and got it checked for free. Big thanks to you guys for the suggestion!

Their report said it's commonly the Mass Airflow sensor. Also, after much research it was suggested to clean the Mass Airflow sensor before replacement. I did that last night. I also tried replacing the Airfilter while I was in there.

Well the Airfilter Autozone gave me did not fit (STP SA5350). So back in went the old filter after I cleaned the MAF filter with CRC MAF cleaner. I took her for a test drive and the SES remains lit.

So before I shell out the $200 or rummage a junkyard looking for new one. Any ideas what the next step should be? I'm a dad of a 3yo & 5yo; so my time is limited. I'm also a newbie to auto mechanics, but more then apt enough to learn.

I have already replaced a few superficial things like foglight bulbs, BMW emblems and it's Grill. Now for the real repairs.

Thanks for your time and any suggestions in getting my vert in tip topless shape!
- Gio.De



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Old 03-03-2017, 05:31 PM   #2
Sansho
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Location: CT
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Do you know exactly what code(s) are being thrown? Can't do much with "AutoZone said .... ". If you need to, go back and have them recheck it, and write down the code(s) that they find.
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Old 03-03-2017, 06:50 PM   #3
Yewzer B Lewzer
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Yes get the codes and don't buy a MAF. MAF's are usually not the problem.

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Old 03-03-2017, 08:42 PM   #4
Giode
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Thanks folks! Yeah, I'm still learning the ropes here. The code was P0102. Thanks for your time and support!


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Old 03-04-2017, 06:51 PM   #5
Dogthebountyhunter
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P0102 is maf sensor. Check the plug connection first. Check and see if the previous owner accidentally plugged alternator plug into the Maf and maf plug into alternator. For some reason my cars previous owner did. The only code it threw was maf not alternator. Cleaning these mafs doesn't really help anything. Check for vacuum leaks as well. If you can't figure it out I would try a new one
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Old 03-04-2017, 08:30 PM   #6
jfoj
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P0102 IS NOT LIKELY THE MAF SENSOR. STOP WITH THE FOOLISHNESS.

First you need to READ and UNDERSTAND the error code description. Kind of a rookie mistake, however, I see PLENTY of seasoned mechanics/technicians make the same mistakes.

You have to understand that the majority if the time if a sensor is mentioned in an error code, the sensor is NOT usually the problem!!

P0102 MAF Circuit Low Input

The VERY first thing to do is unplug the MAF connector and reconnect it to make sure it is fully seated.

You have to isolate the "sensor/actuator" and the "circuit/wiring". These are 2 VERY different parts of the system. OBDII monitors the sensor AND the circuit for problems. Based on the error codes (DTC's) and the descriptions the problem is not likely the sensor/actuator. Freeze Frame data is also very helpful. Gather this data before you clear codes.

Chances are there is a wiring, connections or terminals are the problem. It could be a problem also with contamination in the DME connections as well.

This is kind of hard to explain quickly, but assuming you have a Voltmeter, you can use it to help isolate the problem.

Disconnect the connection to the the sensor/actuator.

Use a small paper clip to probe into the female terminals. With the key on you should typically see a supervisory Voltage across the 2 wires. This may not always be the case, but it is worth checking.

Then check each to both ground and battery positive for Voltage. If you find no Voltage to ether ground or battery positive, then chances is this wire has a problem between the connector and the DME.

The wire could be broken at the female terminal inside the connector, it could be broken inside the insulation somewhere in the wiring harness, it could be broken at a connection point between the sensor/actuator and the DME. The DME could have female terminals backed out of the connector, there could be coolant or oil contamination at the DME connector, the female terminals could be spread too wide and loose from heat cycling or someone sticking too wide of the probe or terminal in the female part for testing.

This should no be rocket science. You should find there is a problem in under 30 minutes, but finding the source of the problem may take much longer.

I would unplug the DME connections and look for coolant/oil in the connectors and look for terminals that have backed out of the connector.

See #6 in this thread - http://forum.e46fanatics.com/showthread.php?t=897616

You can also check the wiring by using an OBDII tool while watching the MAF reading Live on the tool. Wiggle the wiring at the sensor and see if the MAF value drops in and out. Also wiggle the wiring at junction box near the throttle body.

Since you do not have an OBDII tool, read this!

If you have a smart phone or table, get an OBDII App and interface so you can read the codes along with Live/Realtime or Freeze Frame data then you will know exactly what is going on with the engine fuel management system.

The OBDFusion App and proper VeePeak interface from Amazon are less than $30 for both for iProducts, less than $20 for both for Android

OBDFusion for Android is is $3.99.

https://www.amazon.com/Veepeak-Bluet...peak+bluetooth

OBDFusion, for the iProducts it is $9.99.

For iProducts you NEED a Wifi adapter or LE Bluetooth adapter which are more expensive and VeePeak does not offer these yet..

iProducts requires Wifi - https://www.amazon.com/dp/B00WPW6BAE...ywords=veepeak

The adapter links I posted were some of the cheapest and smallest interfaces at the time, you should search and see if there are others that may be slightly cheaper but from what I have found the VeePeak interfaces have few, if any complaints.
__________________
Solve your misfires, lean codes, rough idle - http://forum.e46fanatics.com/showthread.php?t=897616

Fuel pump failures - http://forum.e46fanatics.com/showthread.php?t=929501

Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temp, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

E46/E39 GM5 Door Lock Info - www.bmwgm5.com

Lower hose temp switch O-ring - BMW #13621743299

Last edited by jfoj; 03-04-2017 at 09:16 PM.
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Old 03-04-2017, 09:11 PM   #7
BMWCaptain
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Get yourself and OBD II scan tool and CLEAR your error code. You want to see what actually shows up for an error code after you clear what is there.


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Old 03-05-2017, 12:08 AM   #8
BaliDawg
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Quote:
Originally Posted by BMWCaptain View Post
Get yourself and OBD II scan tool and CLEAR your error code. You want to see what actually shows up for an error code after you clear what is there.
Right, but OP should probably screen shot the freezeframe data before clearing codes.
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Old 03-05-2017, 12:28 PM   #9
Dogthebountyhunter
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Location: Philly
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My Ride: 02 325xi
Quote:
Originally Posted by jfoj View Post
P0102 IS NOT LIKELY THE MAF SENSOR. STOP WITH THE FOOLISHNESS.

First you need to READ and UNDERSTAND the error code description. Kind of a rookie mistake, however, I see PLENTY of seasoned mechanics/technicians make the same mistakes.

You have to understand that the majority if the time if a sensor is mentioned in an error code, the sensor is NOT usually the problem!!

P0102 MAF Circuit Low Input

The VERY first thing to do is unplug the MAF connector and reconnect it to make sure it is fully seated.

You have to isolate the "sensor/actuator" and the "circuit/wiring". These are 2 VERY different parts of the system. OBDII monitors the sensor AND the circuit for problems. Based on the error codes (DTC's) and the descriptions the problem is not likely the sensor/actuator. Freeze Frame data is also very helpful. Gather this data before you clear codes.

Chances are there is a wiring, connections or terminals are the problem. It could be a problem also with contamination in the DME connections as well.

This is kind of hard to explain quickly, but assuming you have a Voltmeter, you can use it to help isolate the problem.

Disconnect the connection to the the sensor/actuator.

Use a small paper clip to probe into the female terminals. With the key on you should typically see a supervisory Voltage across the 2 wires. This may not always be the case, but it is worth checking.

Then check each to both ground and battery positive for Voltage. If you find no Voltage to ether ground or battery positive, then chances is this wire has a problem between the connector and the DME.

The wire could be broken at the female terminal inside the connector, it could be broken inside the insulation somewhere in the wiring harness, it could be broken at a connection point between the sensor/actuator and the DME. The DME could have female terminals backed out of the connector, there could be coolant or oil contamination at the DME connector, the female terminals could be spread too wide and loose from heat cycling or someone sticking too wide of the probe or terminal in the female part for testing.

This should no be rocket science. You should find there is a problem in under 30 minutes, but finding the source of the problem may take much longer.

I would unplug the DME connections and look for coolant/oil in the connectors and look for terminals that have backed out of the connector.

See #6 in this thread - http://forum.e46fanatics.com/showthread.php?t=897616

You can also check the wiring by using an OBDII tool while watching the MAF reading Live on the tool. Wiggle the wiring at the sensor and see if the MAF value drops in and out. Also wiggle the wiring at junction box near the throttle body.

Since you do not have an OBDII tool, read this!

If you have a smart phone or table, get an OBDII App and interface so you can read the codes along with Live/Realtime or Freeze Frame data then you will know exactly what is going on with the engine fuel management system.

The OBDFusion App and proper VeePeak interface from Amazon are less than $30 for both for iProducts, less than $20 for both for Android

OBDFusion for Android is is $3.99.

https://www.amazon.com/Veepeak-Bluet...peak+bluetooth

OBDFusion, for the iProducts it is $9.99.

For iProducts you NEED a Wifi adapter or LE Bluetooth adapter which are more expensive and VeePeak does not offer these yet..

iProducts requires Wifi - https://www.amazon.com/dp/B00WPW6BAE...ywords=veepeak

The adapter links I posted were some of the cheapest and smallest interfaces at the time, you should search and see if there are others that may be slightly cheaper but from what I have found the VeePeak interfaces have few, if any complaints.
How is p0102 not the Maf sensor? I didn't tell him to go order a brand new oem Maf sensor, I said to check the connection first just like you did. I haven't posted anything but sound advice trying to help people with their problems because I've been in the same boat and had to help myself. Every thread I reply to you quote me to tell me I'm wrong even though we practically give the same solutions.

Op have you checked the plug? Did you fix your problem?
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Old 03-05-2017, 12:52 PM   #10
jfoj
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My Ride: 330CiC, M5, X5, E93
P0102 clearly states "MAF circuit low input".

This means the "circuit" or wiring to the MAF is likely the problem, not the actual MAF itself.

You stated
Quote:
Originally Posted by Dogthebountyhunter View Post
P0102 is maf sensor.
This is DANGEROUS on a forum with people that do not really think. They read that and go and replace the MAF sensor.

P0102 is a MAF sensor "circuit" code, very different than the code specific to the sensor.
__________________
Solve your misfires, lean codes, rough idle - http://forum.e46fanatics.com/showthread.php?t=897616

Fuel pump failures - http://forum.e46fanatics.com/showthread.php?t=929501

Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temp, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

E46/E39 GM5 Door Lock Info - www.bmwgm5.com

Lower hose temp switch O-ring - BMW #13621743299
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Old 03-05-2017, 01:44 PM   #11
Dogthebountyhunter
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Join Date: Jul 2016
Location: Philly
Posts: 124
My Ride: 02 325xi
Quote:
Originally Posted by jfoj View Post
P0102 clearly states "MAF circuit low input".

This means the "circuit" or wiring to the MAF is likely the problem, not the actual MAF itself.

You stated

This is DANGEROUS on a forum with people that do not really think. They read that and go and replace the MAF sensor.

P0102 is a MAF sensor "circuit" code, very different than the code specific to the sensor.
Jfoj you are very right. The abundance of new threads asking the same questions has taken its toll on my sanity. There should be some kind of mega sticky people have to read 10 times before they can post a new thread.
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Old 03-05-2017, 10:11 PM   #12
Giode
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Join Date: Jan 2017
Location: 97408
Posts: 3
My Ride: 2001BMW325Ci
Hey guys! Thanks for the input. However, if there are multiple threads on this same topic - I apologize.

I did my best to locate all MAF threads and did not find much to help me. So I appreciate all your help, understanding, kindness and welcoming to this site. Hopefully, I'll be able to contribute myself to help others in the future. Many thanks! - Gio


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