check engine light after COI - Toyota Yaris Forums

scoobopdan · 02-20-2015, 12:41 PM

I installed a CAI yesterday, drove for a total of 2-3 hours between then and now, and the check engine light randomly came on. I'm going to try checking all of the sensors and everything and try resetting it, but in the mean time, can anyone think of what would cause a delayed trip like that?

Betrivent · 02-20-2015, 01:29 PM

COI?

scoobopdan · 02-20-2015, 02:20 PM

jesus my bad, I meant CAI, cold air intake. I just rechecked all the hoses and bolts and reset the CPU. No engine light after a 5 minute idle, so we'll see if it comes back.

Betrivent · 02-20-2015, 02:33 PM

haha! I was trying to think of every single acronym it would be and was drawing a blank. Sometimes when you install a CAI you need to disconnect your battery and let the car re-learn it's idle.

CrankyOldMan · 02-20-2015, 02:36 PM

That's almost always a vacuum leak. Get a can of brake cleaner and lightly spray short bursts around the intake tubing, waiting several seconds between bursts. If the engine surges consistently when you spray a specific spot, you've found the leak.

In my case, the supercharger can pull enough air at high rpm to cause the voltage to go out of range and throw a code, which happens sporadically and can take several minutes to show up. Sometimes a code will only set if the condition happens a certain number of times in a certain time frame. It all just depends on the way it was programmed.

scoobopdan · 02-20-2015, 02:51 PM

Good info. Betrivent - I had disconnected the battery and let it idle when I first did the install. If it comes up again I'll try looking for a leak somewhere. Thanks!

WorkTL · 02-20-2015, 03:08 PM

I would get a new intake. I had the same problem with an Injen intake. Bought the afe and no more head aches.

Betrivent · 02-20-2015, 04:34 PM

What is the diameter of the new one? If it's slightly larger than the original it could be throwing off the ECU as well.

scoobopdan · 02-21-2015, 12:06 PM

It's an injen so the diameter is larger (I don't know for sure but the last car I had one on was 3") but I thought unplugging the battery was supposed to let the ECU restart and account for more air. After driving all day (total of 3+ hours) the light tripped back on randomly. So I guess now I'll check for air leaks?

WeeYari · 02-21-2015, 12:46 PM

The maf is super sensitive and does not like a deviation in volume of air passing over it. Velocity of air is ok, hence the principle of using an intake allow freer movement of air. The ecu cannot accommodate radical deviations in volume introduced by a larger diameter pipe.

Sent from my iPhone using Tapatalk

scoobopdan · 02-21-2015, 07:27 PM

Hm interesting... so is there any way to prevent it from throwing up a code? New MAF? I mean all of the intakes we're throwing on (well atleast 99%) are a much larger diameter than the stock intakes, so if that were the case wouldn't everyone have this issue? I've had to drive the car around today (total of 100 miles or so) and it's been fine, just the check engine light is on.

scoobopdan · 02-21-2015, 07:28 PM

Well I take that back, the idle is a little low. But nothing low enough to make the car shudder or anything, so I don't think that would be throwing the code.

scoobopdan · 02-22-2015, 02:02 PM

So I went to autozone and the code pulled was p441. It says it's from an incorrect emission purge which could be caused by a leak or block in the EVAP line or faulty purge VSV. I haven't even googled it yet, so I apologize if there's already a topic on the code on here but I thought I'd just update this thread.

02-20-2015, 12:41 PM	#1
scoobopdan Drives: 2008 Yaris Join Date: Sep 2014 Location: Austin, TX Posts: 81	check engine light after COI I installed a CAI yesterday, drove for a total of 2-3 hours between then and now, and the check engine light randomly came on. I'm going to try checking all of the sensors and everything and try resetting it, but in the mean time, can anyone think of what would cause a delayed trip like that? Last edited by scoobopdan; 02-20-2015 at 02:20 PM.

02-21-2015, 12:46 PM	#10
WeeYari View User's Garage Drives: 06 Polar White 5dr, 13 Soul 4u Join Date: Oct 2008 Location: Georgetown, Ontario, Canada Posts: 5,740	check engine light after COI The maf is super sensitive and does not like a deviation in volume of air passing over it. Velocity of air is ok, hence the principle of using an intake allow freer movement of air. The ecu cannot accommodate radical deviations in volume introduced by a larger diameter pipe. Sent from my iPhone using Tapatalk __________________

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02-20-2015, 01:29 PM	#2
Betrivent Not quite a noob Drives: e46 325 Join Date: Jul 2009 Location: edmonton Posts: 1,408	COI?

02-20-2015, 02:20 PM	#3
scoobopdan Drives: 2008 Yaris Join Date: Sep 2014 Location: Austin, TX Posts: 81	jesus my bad, I meant CAI, cold air intake. I just rechecked all the hoses and bolts and reset the CPU. No engine light after a 5 minute idle, so we'll see if it comes back.

02-20-2015, 02:33 PM	#4
Betrivent Not quite a noob Drives: e46 325 Join Date: Jul 2009 Location: edmonton Posts: 1,408	haha! I was trying to think of every single acronym it would be and was drawing a blank. Sometimes when you install a CAI you need to disconnect your battery and let the car re-learn it's idle.

02-20-2015, 02:36 PM	#5
CrankyOldMan 2ZR swap. DO IT! Ask how! View User's Garage Drives: 09 Meteoric Metallic HB Join Date: Feb 2011 Location: West Michigan Posts: 2,333	That's almost always a vacuum leak. Get a can of brake cleaner and lightly spray short bursts around the intake tubing, waiting several seconds between bursts. If the engine surges consistently when you spray a specific spot, you've found the leak. In my case, the supercharger can pull enough air at high rpm to cause the voltage to go out of range and throw a code, which happens sporadically and can take several minutes to show up. Sometimes a code will only set if the condition happens a certain number of times in a certain time frame. It all just depends on the way it was programmed.

02-20-2015, 02:51 PM	#6
scoobopdan Drives: 2008 Yaris Join Date: Sep 2014 Location: Austin, TX Posts: 81	Good info. Betrivent - I had disconnected the battery and let it idle when I first did the install. If it comes up again I'll try looking for a leak somewhere. Thanks!

02-20-2015, 03:08 PM	#7
WorkTL View User's Garage Drives: 2013 Yaris LE Join Date: Sep 2014 Location: SoCal Posts: 216	I would get a new intake. I had the same problem with an Injen intake. Bought the afe and no more head aches.

02-20-2015, 04:34 PM	#8
Betrivent Not quite a noob Drives: e46 325 Join Date: Jul 2009 Location: edmonton Posts: 1,408	What is the diameter of the new one? If it's slightly larger than the original it could be throwing off the ECU as well.

02-21-2015, 12:06 PM	#9
scoobopdan Drives: 2008 Yaris Join Date: Sep 2014 Location: Austin, TX Posts: 81	It's an injen so the diameter is larger (I don't know for sure but the last car I had one on was 3") but I thought unplugging the battery was supposed to let the ECU restart and account for more air. After driving all day (total of 3+ hours) the light tripped back on randomly. So I guess now I'll check for air leaks?

02-21-2015, 07:27 PM	#11
scoobopdan Drives: 2008 Yaris Join Date: Sep 2014 Location: Austin, TX Posts: 81	Hm interesting... so is there any way to prevent it from throwing up a code? New MAF? I mean all of the intakes we're throwing on (well atleast 99%) are a much larger diameter than the stock intakes, so if that were the case wouldn't everyone have this issue? I've had to drive the car around today (total of 100 miles or so) and it's been fine, just the check engine light is on.

02-21-2015, 07:28 PM	#12
scoobopdan Drives: 2008 Yaris Join Date: Sep 2014 Location: Austin, TX Posts: 81	Well I take that back, the idle is a little low. But nothing low enough to make the car shudder or anything, so I don't think that would be throwing the code.

02-22-2015, 02:02 PM	#13
scoobopdan Drives: 2008 Yaris Join Date: Sep 2014 Location: Austin, TX Posts: 81	So I went to autozone and the code pulled was p441. It says it's from an incorrect emission purge which could be caused by a leak or block in the EVAP line or faulty purge VSV. I haven't even googled it yet, so I apologize if there's already a topic on the code on here but I thought I'd just update this thread.