Replacing the MAF (mass airflow) sensor

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5chn3ll
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Replacing the MAF (mass airflow) sensor

Post by 5chn3ll » Mon Jan 08, 2018 12:24 pm

The MAF sensor is a common cause for a MIL (check engine light). If you install an aftermarket, oiled air filter, or if you clean and over-oil your aftermarket filter, your MAF stands a good chance of being fouled and needing replacement.

This DIY rates 0 out of 8 bloody knuckles. It's a piece of cake.

Diagnosing your MAF:
The most straightforward diagnosis is any malfunction indicator light (AKA the check engine light) indicating unexpected/out-of-range MAF values. Having both P1128 and P1130 is also a good indication that you need a new MAF, but it isn't a guarantee that the MAF is the issue. If you only have one code, do not clear it. Drive for another couple of days and check again for both P1128 and P1130.

Image

Tools you will need:
A Torx T20 security driver or screwdriver tip. See photo below. If you don't have a security torx bit or driver (the bit is hollow in the center to accept the post in the middle of the screw head), you need to find one.

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No other tools are required.

You will need to obtain a new MAF. Hint: If you don't want to pay $500, go to the Bosch web site and look up which part fits your vehicle. For a 1999 Carrera 4, the part number is Bosch 0280218009, priced on Amazon at $148.02 in March 2013. Bosch warrants the MAF for 12 months, unlimited miles.

The Bosch vehicle part finder URL: boschautoparts.com/VehiclePartFinder/Pages/VehiclePartFinder.aspx

Once the new MAF is in hand, you're ready to go. Open the engine bay. The MAF is circled in the following photo:

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To remove the MAF, you need to pinch the top end of the back side of the connector to make it release.

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When you are pressing down in the right spot (the two parallel lines in the image below), the connector will pop off.

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Once the electrical connector is unplugged, use your T20 driver to remove the two screws holding the MAF in place and remove the MAF from the intake.

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Carefully insert the new MAF into the hole from which you removed the old one. If you don't remember which way it goes, don't worry! The hole is keyed to the shape of the MAF sensor. Once the new sensor is correctly oriented, replace and tighten the two T20 screws.

Finally, carefully plug the electrical connector into the new sensor.

That's it! Use your scantool or Durametric to clear the diagnostic codes (or disconnect the negative lead on the battery for a few minutes), and go spend some of the several hundred bucks you just saved buying the Bosch part and doing the 5-minute install on your own.
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B-ran
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Re: Replacing the MAF (mass airflow) sensor

Post by B-ran » Sun Jan 21, 2018 1:08 pm

It may seem a rather obvious point, but in my humble experience I have found it is best to put the MAF in facing the correct direction. Don’t ask how I know such things....
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B-ran
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Re: Replacing the MAF (mass airflow) sensor

Post by B-ran » Sun Jan 21, 2018 1:09 pm

But by the by, fantastic write up with all those nice full color pictures!
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5chn3ll
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Re: Replacing the MAF (mass airflow) sensor

Post by 5chn3ll » Sun Jan 21, 2018 1:32 pm

B-ran wrote:
Sun Jan 21, 2018 1:08 pm
It may seem a rather obvious point, but in my humble experience I have found it is best to put the MAF in facing the correct direction. Don’t ask how I know such things....
Heh. The factory MAF mounting point is directionally keyed - you can't install the MAF backwards. On aftermarket intakes, though, the pooch can be screwed in this manner. Good point.

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Re: Replacing the MAF (mass airflow) sensor

Post by Tyler H » Sat May 19, 2018 10:31 am

Even if you don't have a MIL, Durametric can reveal a failing or failed MAF. I didn't have any CEL/MIL, but Durametric showed a MAF fault. Reset it and it came back next drive cycle. Put a new MAF in and it no longer shows a fault in Durametric. Could be the placebo effect, but the car seems to run a little smoother, especially at hot idle.

Doesn't hurt to hook it up and scan for anomalies, even if all seems well.

Since I was "parts throwin," I bought a cheap ass Cardone reman from Rockauto for $50 (plus $50 core charge.) This is the Porsche MAF that someone has taken apart with a Dremel, replaced the guts, and sloppily glued it back together. But hey, for $50 it works and it was a good diagnostics tool. I'll order a new one soon and keep it for a known good spare.

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Re: Replacing the MAF (mass airflow) sensor

Post by 5chn3ll » Wed May 23, 2018 10:48 am

Interesting info on the "refurb" MAF source...

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Re: Replacing the MAF (mass airflow) sensor

Post by Water Hound » Thu Jun 14, 2018 7:45 pm

5chn3ll wrote:
Mon Jan 08, 2018 12:24 pm
You will need to obtain a new MAF. Hint: If you don't want to pay $500, go to the Bosch web site and look up which part fits your vehicle. For a 1999 Carrera 4, the part number is Bosch 0280218009, priced on Amazon at $148.02 in March 2013. Bosch warrants the MAF for 12 months, unlimited miles
Update on pricing - June 2018 shows this part on Amazon for $159.94, a modest price increase over that past 5 years. Not as inexpensive as a $50 rock auto.com reman unit but brand new and warrantied.
2004 C2 Cabriolet, Midnight Blue/Savannah Beige
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Re: Replacing the MAF (mass airflow) sensor

Post by Cuda911 » Fri Jun 15, 2018 9:18 am

It's also a good idea to try cleaning the maf sensor wire before replacing the maf. Simply spray it down well with maf cleaner. I always wondered why they use that stupid security type of bolt. I guess it has helped stem that plague of stolen maf sensors.
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Re: Replacing the MAF (mass airflow) sensor

Post by 5chn3ll » Mon Jun 25, 2018 11:43 am

I always assumed the security torx was a built-in competency check...if you don’t have the right tool to proceed, you have no business here.

Sorta like metric in the 90’s...
Cuda911 wrote:
Fri Jun 15, 2018 9:18 am
It's also a good idea to try cleaning the maf sensor wire before replacing the maf. Simply spray it down well with maf cleaner. I always wondered why they use that stupid security type of bolt. I guess it has helped stem that plague of stolen maf sensors.

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Re: Replacing the MAF (mass airflow) sensor

Post by Cuda911 » Thu Jul 05, 2018 12:16 am

Took me five places to find the security bit. Harbor Freight had it. Sears had no idea what I was talking about when I went there. Same at Ace.
Mike
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'68 Ford Custom 500; '70 Plymouth Cuda; '71 Ford Econoline; '73 Porsche 914 1.7, '74 Porsche 914 1.8; '74 Suzuki TC185; '86 Suzuki GS450L; '88 Subaru GL104WD Turbo Limited Edition; '88 Subaru XT; '91 Lexus ES250; '93 Jeep Wrangler, '99 Porsche Boxster, '03 Turbo VW Beetle; '03 Porsche Boxster; '03 Porsche Carrera C2; '07 Porsche Cayman, '14 Porsche Cayman, & a mishmash of other vehicles. And, my Felt mountain bike.

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