CEL Issue via MAF Sensor, Thoughts? - Toyota Yaris Forums

The Architect · 03-29-2009, 07:29 PM

Here's the quick and dirty.

About maybe...2 weeks ago my CEL would come on and go off randomly for periods of time, In the last week to a few days its been more frequent and now it seems to be on permanently. I used a code reader to narrow it down to the MAF Sensor.

I'm using the AFE Stage 2 Intake although I dont see how that could matter because Ive had it problem free for quite some time and even now with the CEL I don't really notice any real issues other than the fact that the light is on.

Not sure if I should bring it to a dealer seeing as how my yaris is heavily modified and they might nit pick.

Thoughts...

changchewsoon · 03-29-2009, 09:43 PM

Yup, a good mechanic should be able to tell you what is wrong, try asking him to clean the MAF first to see whether it helps. It could be some dirt/debris that is trapped or blocking the sensor.

Then, clear the error code in the ECU and drive it for a few days to see how it goes.

m911gt · 03-29-2009, 09:46 PM

my scan gauge indicated a similar problem a couple weeks back, i have the same intake. the problem happened after a really damp day and i had cleaned my engine bay that very same afternoon...i cleared the code the next day and it never came back. i assumed the MAF may have gotten moisture on it when i wiped the bay down.

*tk-421* · 03-29-2009, 10:28 PM

A dirty MAF sensor is a very likely culprit. I've read that cleaning can be accomplished using a compressed air can, but you need to be very gentle or you may damage it.

White Yaris · 03-29-2009, 10:30 PM

1+ to who said dirty MAF, damp weather, and loose MAF.

The Architect · 03-29-2009, 11:07 PM

Well I pulled the MAF out and came to see that it was merely a plastic piece with a small metal rod/ball tucked up inside it (I didnt know this) and it didnt look to be dirty but then again how would I know.

I have compressed air and calm hands should I need to clean it but how would I go about this. Is the metal piece highly sensitive to touch, is there anything i should or should not clean it with...etc....etc

Any and all advice is appreciated.

YarisSedan · 03-29-2009, 11:44 PM

Purchase a can of MAF cleaner and spray it liberally on the sensor wire. You should be able to see lots of dirt buildup. Specially with any type of cone filter if you dont clean them regularly dirt starts to bypass the filter and contaminate the sensor. Think of it as a sponge it can only hold so much water before it starts to leak. Same thing with your filter if you dont take it off and clean it regularly sooner or later dirt wont be trapped anymore. There are a few brands out there of MAF cleaner just go to your local auto parts store and ask for a can.

CTScott · 03-29-2009, 11:44 PM

The metal piece is the intake air temperature sensor. The actual MAF sensor is within the plastic. To clean it you gently blow out the "tunnels" in the plastic part.

CRC makes a MAF cleaner, which is specifically designed for cleaning them, but just blowing out the tunnels usually resolves intermittent issues.

CTScott · 03-29-2009, 11:50 PM

Actually, here's a good write-up on cleaning the Yaris one:

http://www.yarisclubuk.com/forum/viewtopic.php?t=131

03-29-2009, 07:29 PM	#1
The Architect Give Me Resonance View User's Garage Drives: 2007 Yaris HB Join Date: Oct 2008 Location: FL Posts: 648	CEL Issue via MAF Sensor, Thoughts? Here's the quick and dirty. About maybe...2 weeks ago my CEL would come on and go off randomly for periods of time, In the last week to a few days its been more frequent and now it seems to be on permanently. I used a code reader to narrow it down to the MAF Sensor. I'm using the AFE Stage 2 Intake although I dont see how that could matter because Ive had it problem free for quite some time and even now with the CEL I don't really notice any real issues other than the fact that the light is on. Not sure if I should bring it to a dealer seeing as how my yaris is heavily modified and they might nit pick. Thoughts... __________________ (3) 12" Alpine Type R Subs/Hifonics BXi1208D Hifonics ZXi6.5c / 2006 Kicker ZX350.4 Knu Fleks 1/0 Wiring & In Big 3 Optima Yellow Top Battery/Iraggi HO Alternator Alpine CDA-105, KCA-420i/KCA-121b/KCE-400BT PG TLD22 8V Line Driver

03-29-2009, 09:43 PM	#2
changchewsoon View User's Garage Drives: Vios Turbo Join Date: Feb 2009 Location: Malaysia Posts: 190	Yup, a good mechanic should be able to tell you what is wrong, try asking him to clean the MAF first to see whether it helps. It could be some dirt/debris that is trapped or blocking the sensor. Then, clear the error code in the ECU and drive it for a few days to see how it goes. __________________ 454 whp, 1.7 bar boost, pump gas, water/meth. 501 whp, 2.2 bar boost, pump gas + avgas, no water/meth. www.viosturbo.com - World's first 500 WHP 1NZ-FE

03-29-2009, 09:46 PM	#3
m911gt Carless in Chicago View User's Garage Drives: 08 Blk LB Join Date: Oct 2008 Location: Chicago Posts: 2,479	my scan gauge indicated a similar problem a couple weeks back, i have the same intake. the problem happened after a really damp day and i had cleaned my engine bay that very same afternoon...i cleared the code the next day and it never came back. i assumed the MAF may have gotten moisture on it when i wiped the bay down. __________________ Wanted: Forced Induction Some say that he is the secret love child of Ferrari and Porsche, and others say that he would lap James May twice in a 1/4 mile drag race. All we know is that he is called The Stig.

03-29-2009, 10:28 PM	#4
tk-421 Super Moderator View User's Garage Drives: 5D-07-LB Join Date: Jan 2007 Location: Dagobah Posts: 4,263	A dirty MAF sensor is a very likely culprit. I've read that cleaning can be accomplished using a compressed air can, but you need to be very gentle or you may damage it. __________________ --[ FORUM RULES ]--[ SEARCHING TIPS ]--[ EYELIDS PICS ]--[ RBK SPOILER ]--[ BEST/WORST INVESTMENTS ]-- Last edited by tk-421; 03-30-2009 at 03:23 AM.

03-29-2009, 10:30 PM	#5
White Yaris Broke Tuner View User's Garage Drives: White Yaris Join Date: Oct 2008 Location: Warm Orange County Posts: 146	1+ to who said dirty MAF, damp weather, and loose MAF. __________________ EVERYTHING YOU KNOW IS WRONG

03-29-2009, 11:07 PM	#6
The Architect Give Me Resonance View User's Garage Drives: 2007 Yaris HB Join Date: Oct 2008 Location: FL Posts: 648	Well I pulled the MAF out and came to see that it was merely a plastic piece with a small metal rod/ball tucked up inside it (I didnt know this) and it didnt look to be dirty but then again how would I know. I have compressed air and calm hands should I need to clean it but how would I go about this. Is the metal piece highly sensitive to touch, is there anything i should or should not clean it with...etc....etc Any and all advice is appreciated. __________________ (3) 12" Alpine Type R Subs/Hifonics BXi1208D Hifonics ZXi6.5c / 2006 Kicker ZX350.4 Knu Fleks 1/0 Wiring & In Big 3 Optima Yellow Top Battery/Iraggi HO Alternator Alpine CDA-105, KCA-420i/KCA-121b/KCE-400BT PG TLD22 8V Line Driver

03-29-2009, 11:44 PM	#7
YarisSedan Drives: 08 Yaris Sedan Join Date: Oct 2008 Location: California - Bay Area Posts: 2,773	Purchase a can of MAF cleaner and spray it liberally on the sensor wire. You should be able to see lots of dirt buildup. Specially with any type of cone filter if you dont clean them regularly dirt starts to bypass the filter and contaminate the sensor. Think of it as a sponge it can only hold so much water before it starts to leak. Same thing with your filter if you dont take it off and clean it regularly sooner or later dirt wont be trapped anymore. There are a few brands out there of MAF cleaner just go to your local auto parts store and ask for a can. __________________ http://www.cardomain.com/ride/3210549

03-29-2009, 11:44 PM	#8
CTScott ULTIMATE View User's Garage Drives: 09 5dr LB, 2x 08 3dr LB Join Date: Oct 2008 Location: USA, CT Posts: 13,460	The metal piece is the intake air temperature sensor. The actual MAF sensor is within the plastic. To clean it you gently blow out the "tunnels" in the plastic part. CRC makes a MAF cleaner, which is specifically designed for cleaning them, but just blowing out the tunnels usually resolves intermittent issues.

03-29-2009, 11:50 PM	#9
CTScott ULTIMATE View User's Garage Drives: 09 5dr LB, 2x 08 3dr LB Join Date: Oct 2008 Location: USA, CT Posts: 13,460	Actually, here's a good write-up on cleaning the Yaris one: http://www.yarisclubuk.com/forum/viewtopic.php?t=131

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