Check Engine Light (air filter)

[Likesavinggas]

Hello, I own a 2007 Yaris and it's been a good car for these many years, just one repair last year to replace the water pump (bad bearing). It was still working fine when replaced (no check engine light). Recently I realized that the original engine air filter was still in place (for 18 years, ugh). So I bought a new filter and things seemed fine until the check engine light came on about a week later. This was the very first time the CE light had ever lit up. So after removing it and re-installing the filter again the CE light came on again (had to disconnect battery to deactivate the light, but it came back on again later). The error code indicated the light had something to do with the air filter system so I figured it must be the new filter?

Anyways, I put the old air filter back in place and deactivated the CE light again. If it does not light up in the next few days I'll assume the new filter is the cause. I'll return here to update soon and if the CE light does not come back on I'll go to the dealership to buy a real Toyota air filter and see what happens. Otherwise I have no complaints about my 2007 Yaris other than the old paint job looking bad now. Has anyone here had a similar air filter problem? Thanks

[komichal]

I cannot imagine how a new air filter can bring up CEL.
If the error comes again, type the exact error here.
Do you have a picture of this 18 years old air filter? I cannot imaginge how it looks, especially when I need to change it twice a year (living next to a lime quarry).

Anyway, I would suspect that during the filter change procedure a piece of dust may have flew off the filter and maybe hit the MAF sensor or got stuck in a throttle body. If the filter was not changed for 18 years we can assume that there was no cleaning of MAF or throttle body as well. These would be my primary points of interest.

I could also imagine some dramatic way of changing filter so that the whole airbox gets moved a bit, resulting in fake air being sucked in and "too lean" error. But lets start with cleaning up the airbox, MAF sensor and throttle body.

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18 years.... omg... do you change oil, oil filter, brake fluid?

[Likesavinggas]

Thanks for replying, yes I keep up with all other aspects, oil, etc. The old filter is back in place so a pic isn't possible at this time (it was black). So far after 3 days of driving the CE light has not come back on. Will give it some more time and get back with you later.

[ex-x-fire]

I'd put the new filter back in, clear the codes, and unhook the battery to start off fresh.

[Likesavinggas]

Update : Ok, after 4-5 days and ~150 miles of driving with the old filter back in place the check engine light has Not come back on. Beforehand, with the new filter in place the light came on after just 50 miles of driving (twice after deactivating the CE light). So the problem does not seem to be anything other than the new filter, at least so far anyways. I will leave the old filter in place for a while longer to see if the EC light comes back on.

Komichal, do you mind if I ask what brand of air fitler you use? Is it an original Toyota part? The one I bought via Amazon is a PHILTOP Engine Air Filter which is supposed to be for my 2007 Yaris and it does appear as an identical match to the old filter. Both filters seem to fit perfectly into the filter box and all henges and latches lock into place a-ok.

[komichal]

Well as I am changing often (because of visual layer of dust on it) I tried many brands, they all worked just fine.
Denckermann, Mann, Hengst... all good. No Philtop brand here for me to check.
No matter if it cost 2 or 10 bucks, they delivered the same performance. I have never noticed a difference nor a problem with CEL came up.
Maybe if the new filter is too dense and the ECU evaluates the air path as clogged?
ex-x-fire made a good comment about total reset by unhooking the battery for a while. That should reset the ECU. If that does not help you can try to buy some cheap filter and put it in to see what happens.

[Likesavinggas]

Thanks Komichal and all for your replies. As mentioned in my previous posts I have deactivated the EC light a few times while testing out both the new & old filter (again). Update : after a week running on the old filter the CE light did come back on (after ~200 miles driving). So yesterday I deactivated the light again and reinstalled the new filter. I have triple checked the installation to make certain the new filter was seated properly and all hinges and latches locked a-ok, no leaks detected visually.

The engine sounds perfectly normal with both filters, no hesitation, no stalling, nothing unusual when driving slow, fast, or accelerating, and easy to start. We'll start to drive the Yaris again today to see if/when the CE light comes back on. Seems hard to believe a new filter would restrict air intake more than the old filter, but maybe the sensor doesn't like the extra clean air now, ha.
Anyways this is my last shot at figuring out the EC light assuming it comes back on this time. I have read that if it starts to blink then the problem is getting serious. I'll attach a pic of the old filter, even sunlight does not penetrate it.
63011

[Likesavinggas]

We drove the Yaris 40 miles today, no CE light yet with the new filter re-installed. Will update in the coming days if or if not the CE light comes back on...

[komichal]

how did you deactivate the CE light? If you did so by disconnecting battery for some time then this also resets the ECU, but if you deactivated it using OBD diagnostics error reset then this does not reset the ECU and it still remembers all values it learnt so far.

So to sum it up:
1. Make sure the battery has been disconnected for a few minutes.
2. If the error comes back, read the code and post it here

[Likesavinggas]

Yes I deactivated the CE light each time by disconnecting the battery for a few minutes and also tapping the horn to fully drain any capacitors which might be still energized. I went to Advance Auto for their free CE light code reading 2 weeks ago for this diagnostic test and it indicated that the issue was with the engine air intake system (listing several possibilities and nothing specific). I have the print out in the garage but it's raining hard now and will retrieve it later to post the code when I get a chance. None of this started (EC light) until a few days after I first installed the new filter.

[WeeYari]

I don't believe you've ever answered the question about cleaning the MAF sensor.

[Likesavinggas]

My apologies, I overlooked the MAP reference to look it up later. I'll get back to the thread in a day or two once I better understand the procedures and explain why I haven't gotten that far into it, yet.

[Likesavinggas]

Update : Ok, The reason I haven't gotten as far to check out the MAP is that I'm still in the troubleshooting stage to determine if the new air filter or its possible improper installation is the reason the CE light comes on after driving for several days. I'm no mechanic so I'm a bit reluctant to dive further into the MAP inspection but from the description of the possible problems (from the test re-out) it doesn't sound like the MAP is the reason for the EC light. The Yaris has shown no suggested possible problems when starting or running, no hesitation, no issues with acceleration, no sign of power reduction, etc. The engine runs very smoothly and normally. The MAP wiring appears well connected, good and clean and if there were a wiring/connection issue I would expect the EC light to come on immediately and not take several days and many miles to light up (although I could be wrong about that, not a mechanic as said). At this point I may just leave the new filter in place and see if/when the EC light comes back on. If it does come back on I may just ignore it for now and monitor the gas mileage to see if it drops and if the engine performance changes for the worse.

At this point digging into the MAP to inspect it might make matters worse since it's a 2007 model and I'd rather now screw up a component that appears to be working ok. I really appreciate the advice given from all posters and if anything changes in the coming weeks I'll be back with an update. In the meantime I will search for more info on my Yaris model and review videos on how to properly inspect and clean the MAP if it comes down to that. Thanks again, and if anyone knows of an instructional MAP maintenance video specifically for my 2007 2 door hatchback Yaris please do share it.

[WeeYari]

MAF not MAP

The magic in the MAF is two tiny filament wires inside the MAF housing. These measure the rate of air flow passing by them and they can develop a coating of gunk over the years which needs to be cleaned off. There is nothing unique about a Yaris MAF to concern yourself with.

[komichal]

If your profile is correct and you are from Virginia you are most probably having a Yaris with an engine that was not sold in Europe so I have no personal experience with that, however taking the MAF out should be fairly easy - two bolts out, disconnect wiring, gently pull it out while twisting a little clockwise and counterclockwise. There is no bayonet or anything. Just a big silicon o-ring that comes out with the sensor easily.

Once it is out, spray it generously with MAF sensor cleaner (do not use brake cleaner or throttle body cleaner as these can leave residues). MAF sensor does not leave any and means no harm to the electronics. You need really to spray it generously INSIDE the sensor. As WeeYari mentioned, the MAF sensor is made of two tiny wires buried deep in the sensor so you need to hit them with that spray a few times. DO NOT TRY TO BRUSH THEM.
Apart from these two wires you may also notice a little "droplet-like" bubble which I believe is a thermometer for air intake. Spray that one too.

Once it is done, let it dry - the cleaner dries quickly. Once it is dry, gently push it back in, secure with the bolts, connect wiring.

Disconnect battery once again for a minute so that the ECU forgets what it knew from the dirty MAF.

It would really help with the debugging if you can get yourself and OBD reader and get the exact error code the ECU throws. Like P0171 or something like that. These are like 6 USD (https://www.amazon.com/NYTKL-ELM327-OBDII-Diagnostic-Scanner/dp/B0F62RX7YV/ref=sr_1_3?crid=522JF36MDJYC&dib=eyJ2IjoiMSJ9.oHn5LSaqLqc_4AWixAWaW8wCM8_dTnzC5 b5fTjHnTyGX1M46UvuiOYbZyPOwjQD4SBcb7kREncBeBaL5yU5 Qe4bFLA5J_FwRYfKpIHMWr0FUPGEI6qz5qaTVpPzw2UrsFamLD XeK1l99u0rUyQsc2aReyOAX8kKwX0btmMmvXRscuGET9M7mE0K Xbqi425jE-0c-lG40-kyI0WBzuHk4apkf6S6avinc-o8fZ-NUyHtyQ8gikkP1Zm0i4Sqk4uBV9TWNuJ3ne7pxYJi9ZpZaOOp2 yosjeNrJd2uTCFbVOyE.Grj607jcJlaJe7_ljQkbxhN34PY26l DKOxAQFb0lrgQ&dib_tag=se&keywords=ELM327&qid=1748806479&refinements=p_36%3A-1000&rnid=386419011&sprefix=elm327%2Caps%2C202&sr=8-3&th=1) per piece.

[komichal]

If your profile is correct and you are from Virginia you are most probably having a Yaris with an engine that was not sold in Europe so I have no personal experience with that, however taking the MAF out should be fairly easy - two bolts out, disconnect wiring, gently pull it out while twisting a little clockwise and counterclockwise. There is no bayonet or anything. Just a big silicon o-ring that comes out with the sensor easily.

Once it is out, spray it generously with MAF sensor cleaner (do not use brake cleaner or throttle body cleaner as these can leave residues). MAF sensor does not leave any and means no harm to the electronics. You need really to spray it generously INSIDE the sensor. As WeeYari mentioned, the MAF sensor is made of two tiny wires buried deep in the sensor so you need to hit them with that spray a few times. DO NOT TRY TO BRUSH THEM.
Apart from these two wires you may also notice a little "droplet-like" bubble which I believe is a thermometer for air intake. Spray that one too.

Once it is done, let it dry - the cleaner dries quickly. Once it is dry, gently push it back in, secure with the bolts, connect wiring.

Disconnect battery once again for a minute so that the ECU forgets what it knew from the dirty MAF.

It would really help with the debugging if you can get yourself and OBD reader and get the exact error code the ECU throws. Like P0171 or something like that. These are like 6 USD (https://www.amazon.com/NYTKL-ELM327-OBDII-Diagnostic-Scanner/dp/B0F62RX7YV/ref=sr_1_3?crid=522JF36MDJYC&dib=eyJ2IjoiMSJ9.oHn5LSaqLqc_4AWixAWaW8wCM8_dTnzC5 b5fTjHnTyGX1M46UvuiOYbZyPOwjQD4SBcb7kREncBeBaL5yU5 Qe4bFLA5J_FwRYfKpIHMWr0FUPGEI6qz5qaTVpPzw2UrsFamLD XeK1l99u0rUyQsc2aReyOAX8kKwX0btmMmvXRscuGET9M7mE0K Xbqi425jE-0c-lG40-kyI0WBzuHk4apkf6S6avinc-o8fZ-NUyHtyQ8gikkP1Zm0i4Sqk4uBV9TWNuJ3ne7pxYJi9ZpZaOOp2 yosjeNrJd2uTCFbVOyE.Grj607jcJlaJe7_ljQkbxhN34PY26l DKOxAQFb0lrgQ&dib_tag=se&keywords=ELM327&qid=1748806479&refinements=p_36%3A-1000&rnid=386419011&sprefix=elm327%2Caps%2C202&sr=8-3&th=1) per piece.

[Likesavinggas]

Thank you all for the replies. Since my last visit to this site I've been too busy with some family issues to get back here and/or follow your good advice to clean up the MAP. In the coming days I will carefully perform the MAP cleaning with the proper cleaning solution. The CE light did eventually come back on with the new air filter re-installed so it must be the MAP. I shall return, sorry for not replying sooner but at present I do not recieve your replies in my email.

[Likesavinggas]

Ok, one last question before I perform the MAP cleaning. I ordered a can of CRC MAP Sensor Cleaner and have reviewed the instructions (also have viewed several utubes on how to do it). On the can it says "Do Not use on a vehicle with a Karman Vortex air flow sensor e.g. on some 2006 and older Toyotas" I would assume that my 2007 Yaris is ok?, but would like an expert here to confirm that my Yaris does not use a Karman Vortex air flow sensor. Thanks for your guidance on this.

Also, in a couple of those youtubes the mechanic would keep the engine running while unplugging the MAP sensor. They did this to show that if the engine stopped running then the MAP sensor was working as it should (though it still may need cleaning), but if the engine kept running then the MAP sensor was defective. Would you recommend this step?

[Likesavinggas]

Ok, back now with some updates. I finally got around to cleaning the MAP as per instructed. The wiring attachment came off smoothly, no corrosion or other defects were visible. When I removed the MAP it looked pretty clean to me, no soot on the silvery wires but the little bulb on the tip was very dark in color. I sprayed it down carefully and compleltely but the tip remained dark. After googling up some 2017 Yaris MAP images I now see that the tip is dark in those pics too (brand new) so I assume that's a normal color. I then disconnected the battery to reset the check engine light so we'll know in 2-3 days of driving if it comes back on or not. In the meantime if anyone has any other suggestings I open to them. Thanks, I will return once I'm certain if the light comes back on or not.

[Likesavinggas]

^^^ PS, I forgot to mention that after the MAP cleaning the engine sounded a lot smoother, it didn't rev up for a couple of seconds like before the cleaning. I actually had to step outside to hear it running. That should be a good sign, fingers crossed.

[Likesavinggas]

Drat. After cleaning the MAP the check engine light came on again after 3 days of driving. I'll take the car back to Advanceauto and have them run the diagnostic again to see if it's the same problem related to the air filter/MAP/intake. Meanwhile the Car runs fine, ugh. I'm still open to other advice. Thanks.

[komichal]

I can only repeat what I wrote before:

It would really help with the debugging if you can get yourself and OBD reader and get the exact error code the ECU throws. Like P0171 or something like that. These OBD readers are like 6 USD per piece.

[Likesavinggas]

Thanks Komichal, I'm now getting these replies in my email. I have to confess that I'm not up to speed on some of this (too old, ha). But when I last went to Advance Auto they performed the following as presented from their website:

"To better diagnose your engine issues, we’ll scan your OBD-II vehicle for free. If additional diagnoses are needed we’ll help you find a local technician. Available for most OBD-II vehicles.".

Is what you're suggesting any different or more specific? Their analysis indicated a possible problem with the air filter or MAP, both of which I have replaced and cleaned. I plan to return there for another reading just in case I did fix the MAP issue but maybe something else is now activating the check engine light? A long shot I know.
Again, thanks for hanging in there with my long saga.

[Likesavinggas]

Update - Good news I hope?
Well, after a few weeks where the engine light came back on (after MAP cleaning) it finally went off 2 days ago. I was getting ready to buy a real Toyota replacement air filter to install to see if that would solve the problem but now it seems to be ok. At first I thought that the check engine light bulb had burned out but it still comes on briefly when the engine is started (like all of the dash lights do for a few seconds) so the light still works. If it stays off then I'll assume the issue has resolved itself. There never were any noticeable problems (no engine stalling, no rough running, no black exhaust smoke, etc) so the problem may have just been barely marginable.
I'll now close this thread unless someone has something to add, or unless the check engine light comes back on soon. Thanks again for all the feedback and helpful advice.

[ohms]

you should be ok, i hope! also, auto parts stores will give you a print out of any codes they get when they plugged their scanner in, just so you know for next time!