It looks like there is a hose coupler between those parts. One side is meant to come apart for service and that has a spring clamp. The other side has a crimp clamp and is not normally removed. Do what shadowfax suggested to separate the rubber hose from the intake.
On my 2006 NIssan Xtrail, it was in between the ribs that was cracked and had a hole in it, letting in unmetered air after the MAF. It was on the underside, and obvious once the part was actually removed. I really feel now you were being ripped off. The joke is you did not even describe any symptoms. Was the check engine light even on when you brought it in for the oil change?
The check engine light was on when I went to the dealership to get my oil change. It just came on about two weeks before.
I have an update on this. I purchased a maf sensor off of Amazon. I’ve driven it for 50 miles since replacing and the light is still on. Took it to AutoZone to get the code checked again and the same codes are still showing.
This morning when starting my car/allowing it to warm up, the engine sort of revved. The car was still in park and I was sitting in my garage. The rpms jumped from 1.25 to over 1.5 when the engine revved on its own.
Another thing I noticed was that my car normally makes a clunk noise when first driving. As soon as my speedometer hits exactly 30 mph. it makes this noise. It has done so since I got the car. It is supposedly the abs kicking on. This is common for 2012 Altima’s from what I’ve read. What’s weird is that this clunk has gone away the last few weeks since the service engine light had been on. Not sure if it is just a coincidence???
Any insight on this? Is the revving while idle common if the issue had not been fixed? I was planning to disconnect my battery to reset the check engine light, but now I’m worried that the issue isn’t fixed.
ABS “clunk” is indeed normal.
You can disconnect the battery, it will not make anything worse.
If you can get AutoZone guys to “clear” the code for you, it will be better, as you will have your engine warm, and then if after clearing the code you let engine idle for 20-25 minutes, it will re-calibrate MAF for you.
You must re-calibrate after replacing MAF, and you have to have engine warm to properly calibrate.
Do not rev the engine during this time, let it idle.
Yikes! It’s possibly normal on a Nissan or some other Asian mobile, but has never been normal or present on any ABS cars I own or have owned and they’ve all had fully functional ABS.
“Normal” clunk? What’s up with that? That’s a new one on me!
CSA
It’s just an ABS self test. Maybe yours doesn’t clunk because American cars don’t work?
(I kid, put the knife down.) 
1 Like
My GM cars don’t make any observable test, although one must be performed? However, my 24 year-old daily driver (down south) Dodge Caravan makes a faint “crunch” sound when placed in “drive” and just beginning to move off, and sometimes I don’t even notice it. That is the ABS system checking. The other daily driver here, Pontiac Grand Prix emits no audible sounds which is similar to the “fleet” of GM cars left up north.
If it was the biggest problem with Altima, I would feel blessed
1 Like
When I worked at AZ, we were not allowed to clear codes, just read them. I believe this would have put us in the realm of being a repair shop in the eyes of the law. Of course, if a customer borrowed our code reader and “accidentally” hit the erase button… 
I would never guess… but probably such “accidents” happen once in while 
I really think you need to resolve engine issues. I will also suggest that you ask a question or two over at Nissan Forums, and get some specific advice for your model. If yours revs are bouncing while in Park or Neutral you need to have some relearn procedures done.
https://www.youtube.com/watch?v=W1bsUedze5M.
If you disconnected the throttle body wire harness you need to do this for sure. I don’t remember the MAF being disconnected causing problems. However, I worry that if you bought a really cheap no-name part it could be the problem. With Nissans for stuff like sensors despite costing more its best to stay with OE, otherwise, try and find the equivalent part from the company that supplied Nissan-- Not sure of MAF but Hitachi most likely.I very much doubt yours was bad and required more than a simple cleaning. Also, make sure your air filter is seated properly and that it’s closed properly all around. I hope you figure it all out at soon.
Thanks Michael. Where is the best place to buy a “Hitachi” sensor for a 2012 Altima Coupe 2.5S?
I did purchase maf cleaner and that didn’t do the trick so I purchased a new sensor on Amazon. It didn’t have great reviews but I bought it anyway.
Last night, I disconnected the battery in my car to remove the service engine light. Drove a little and hasn’t come back on.
I think I’m going to put my old sensor back in, return this to Amazon, and purchase the Hitachi one if the light comes back on.
I buy auto parts from Rock Auto online. I find their website to be very user friendly. Shipping is fast (I’ve had orders ship hours after ordering, same day). I always just opt for the cheapest shipping and get parts very quickly. Tracking the order is easy, too.
Using the “look-up” feature for finding your car and then drilling down to the parts you’re after will direct you to what is usually several parts for your make/model from different manufacturers at several price points. “Red hearts” icons are supposed to be best sellers or you can usually stick with OEM parts.
Prices are highly competitive, they stock parts and I’ve not had any go on back order. Clicking links at the parts description will often take you to the manufacturer’s site and will give more specifics, including warranty information. Since prices are so low it’s tough to find any discount codes, but one can usually find a 5% off code and it often will cover the shipping cost, depending on the expense of the parts.
They rock!
CSA
1 Like
The did not have great reviews part was not enough ? Use local parts stores at least that way you don’t have to mess with shipping things back.
Is it possible for a faulty MAF sensor to cause a large drop in MPG?
I would agree with that advice when somebody is trying to repair a car by replacing parts until it’s fixed, rather than completely diagnosing the issue, however, I’m thinking most parts stores would not take back tried or used parts, especially electric/electronic pieces. But Amazon?
I order from rock auto AFTER I know what I need, parts for a complete brake job, spark plugs, headlight relay, etcetera, as examples.
Would you mind paying full price for a part at your local parts store for a tried/used part that some DIY repair by educated guess guy, returned?
CSA
if you cleaned MAF and did not clear code and did not do recalibration → you did part of what has to be done only and you did not even have a chance to properly assess results
by buying non-OEM (and worse “bad reviews”) sensor, you made things worse actually
once you install any MAF, which ECU of the car was not calibrated with, you must recalibrate, period
entirely possible
my advise would be:
- Install you old (“cleaned”) MAF
- disconnect battery overnight
- start it in the morning and let it idle for 25-30 minutes
most likely your issues of Check Engine light and MPG drop will be resoled at this point
Thanks green dragon! I appreciate the help! I am just curious. Why would this sensor effect gas milage?
imagine next [theoretical] scenario:
- let’s imagine you calibrated your sensor at idle speed, as appropriate for your 2.5 engine
- at this point, your ECU “knows” the proper readings for the known air volume at idle, so it can apply its air/fuel tables based on MAF readings
- now, you start driving under load, but your MAF is reporting the volume with some “delta” between what it reports to compare to proepr OEM sensor
- your ECU will detect that and will start compensating for this condition using air/fuel ratio sensor feedback, but this will happen with quite a delay and mostly on steady loads, during variations it will likely have some mistake, as your MAF readings are not in the expected range
- so far it was assumed that non-OEM sensor has the same volume->reading feedback curve and it is only a linear delta, but how do we know it is a fact, it may throw yet another monkey wrench here and cause more fuel dosage mistakes
- these mistakes will accumulate and you will observe it as MPG decrease