Check Engine Light P0172

[masarwar]

Hi Everyone!

New 1999 mx-5 owner here and I LOVE the miata! got it about 2 weeks ago and just love how it handles and rides. Came from a 1995 dodge stealth R/T to this and love it every bit.

I bought this vehicle 2 weeks back and I am in the process to fix some of the minor issues (related to handling and suspension, changed front tires, found out that the front driver side shock was leaking so replacing the pair and also replacing all the brakes). Today on driving from home to work my Check engine light came on. I took it to an auto store here and they told me the code was p0172.

I have been reading about this and it seems that this could be caused by a few different things. I dont have any hesitation or lagging. My car doesnt stall. I do have a bit of rough idle at around 800 rpm (the car just jitters a bit but it is like that on every stop or when i start the car). Cold start RPM is around 1200 then it goes down to 800.

I was wondering if someone would have any idea about this? the car is stock but it does have a K&N Air filter (cone shaped).

Thanks you

[NCGreasemonkey]

Loose the K&N. Get some Quick Dry Electronics cleaner from your auto parts store when you pick up your non-oiled filter. Use the QD to clean the hot wires inside your MAF sensor. Bet the code goes away.

[Joshuates5]

The same thing happened to my e39, everything read ok. The problem ended up being a vacuum hose was broken. Check your hoses that could be the culprit. If so replace and the check engine light should go out.

[NCGreasemonkey]

The same thing happened to my e39, everything read ok. The problem ended up being a vacuum hose was broken. Check your hoses that could be the culprit. If so replace and the check engine light should go out.

On Bimmers it is hoses. The contained PCV system that has the flame-trap is a Germen work of $$$ for any wrench-turner that want to work on them. I love 'em!

I'll bet a shiny nickle that this is an over-oiled K&N that has coated the MAF's hot wires and it is under reading incoming air so it is pulling fuel out of the trims like crazy. Bad thing is that the car is being run lean and it doesn't know it.

[— kung fu jesus —]

New MAF cleared it on my 10ae.

[NCGreasemonkey]

Also. Post up a New member thread so we know who your are.

If the clean and new air filter doesn't work pull and block the vacuum line to the fuel pressure regulator and look at the nipple you pulled it off of. If you see or smell fuel, BINGO!

KFI is a wizard at posts for DIY projects. Wish I could have bumped into to you, KFJ, on my ATL. parts run to Chase and Miguel.

[— Agent☣Orange —]

I heard that KFJ actually audits the IRS.

[— kung fu jesus —]

Ugh. As a SP/consultant, my taxes would make your toes curl. I have had acquaintances who play fast and loose with their deductions, but I don't have the time to waste getting audited. The IRS has targeted small businesses over the past decade.

I remember pulling the MAF on the 10ae to clean it. The little sensor in it didn't look clean, so I touched it...don't do that. I broke it off and had to buy a new one.

[NCGreasemonkey]

Yes, the hot wires are fragile! Spray and air dry. Only!

[masarwar]

Hi everyone,

thank you for the responses. I do appologize had some family issues come up and had to deal with that. So here is the update. I havent taken out the K&N air filter yet as i dont have the oem air filter (the car like this with the K&N air filter). I have gotten an obd2 adapter and the torque pro app and so far all the readings look ok. If i clear the code and the drive the car normal then no codes. the only time the code will appear back is when i am on the highway and going 120+ kmph (around 80 mph). Since getting this code i have cleaned the MAF, cleaned the K&N and reoiled it making sure not to overoil it. Also checked the EGR valve and it was clean.

the car itself drives very well with no idle issues or stalling. When monitoring the OBD2 it looks fine as well. My only issue is that if this is caused by the K&N filter then this should be an issue when i picked up the car and drove over 500 kms back to home the light woud have come on. Really stumped.


One thing that i have been looking into is a vaccum line. I had to take the car in for an oil change and it took 3 mechanics to get the filter out. Apparently they couldnt reach it and had to use this plier like mechanism to get it out. I am reading online that people have said that it is easy to knock out the vacuum line while doing this? The O2 sensor voltage reads normal and so does MAF when driving. I plan on installing a new MAF soon but i dont want to spend the money if this unit is working just fine. Thank you for your advices everyone.

[masarwar]

Also. Post up a New member thread so we know who your are.

If the clean and new air filter doesn't work pull and block the vacuum line to the fuel pressure regulator and look at the nipple you pulled it off of. If you see or smell fuel, BINGO!

KFI is a wizard at posts for DIY projects. Wish I could have bumped into to you, KFJ, on my ATL. parts run to Chase and Miguel.

Hi, thank you i will find the new member thread and will do