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11-24-2014, 11:37 PM | #1 |
Drives: 2009 Yaris Join Date: Nov 2014
Location: Illinois
Posts: 6
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Poor Gas Mileage, No CE Light but many codes
I noticed that my highway mileage has dropped to about 35 mpg so I hooked up the handy OBD monitor and had 16 codes!! These included Mass Air Flow Circuit Malfunction, Mass Flow Low and High Input, Throttle switch malfunction, Engine coolant high input temperature, o2 heater malfunction, crankshaft position sensor circuit malfunction, and of course the good old assorted cylinder misfire (yeah). But the car still runs OK! Had a new mass flow so I changed it out for good measure with no improvement. Any idea what I should try next. I was kinda thinking about the Crankshaft or O2 sensor. Should be interesting thanks!
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11-24-2014, 11:40 PM | #2 |
ULTIMATE
Drives: 09 5dr LB, 2x 08 3dr LB Join Date: Oct 2008
Location: USA, CT
Posts: 13,460
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With that many codes, I would check the battery and alternator. Either of them failing could cause issues for the ECM.
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11-25-2014, 12:07 AM | #3 |
Drives: 2009 Yaris Join Date: Nov 2014
Location: Illinois
Posts: 6
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Thanks Scott for the cruise control DIY!! I installed mine last week and it works great! Back to my problem, I did check the battery voltage with a live OBD monitor and it showed good battery voltage with a slightly higher voltage from the alternator when charging.
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11-25-2014, 06:26 AM | #4 | |
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Drives: 09 5dr LB, 2x 08 3dr LB Join Date: Oct 2008
Location: USA, CT
Posts: 13,460
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Quote:
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11-25-2014, 08:19 AM | #5 |
Drives: 2009 Yaris Join Date: Nov 2014
Location: Illinois
Posts: 6
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Luckily I have a second reader and it confirms the codes. It appears that these are extended codes that would cause issues with a pollution check but are not yet bad enough to throw an actual code. When I unplug any of the sensors I get an immediate check engine light so something in the system must be acting strange. It seems like all of the codes are connected except for the engine coolant high temperature. I am wondering if a O2 sensor not reaching temperature could cause all the rest.
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11-25-2014, 08:26 AM | #6 | |
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Drives: 09 5dr LB, 2x 08 3dr LB Join Date: Oct 2008
Location: USA, CT
Posts: 13,460
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Quote:
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11-25-2014, 09:57 AM | #7 |
Drives: 2009 Yaris Join Date: Nov 2014
Location: Illinois
Posts: 6
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Good thought, I hadn't really considered this possibility as all of the wiring was already in place but it would be worthwile to disconnect and see if the codes go away. I will give this a shot tonight and let you know! The timing for the mileage change does coincide pretty close with the installation.
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11-25-2014, 11:36 AM | #8 | |
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Drives: 09 5dr LB, 2x 08 3dr LB Join Date: Oct 2008
Location: USA, CT
Posts: 13,460
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Quote:
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11-25-2014, 03:14 PM | #9 | |
Drives: 2009 Base Hatch 2 Dr Auto Join Date: Dec 2008
Location: nj
Posts: 4,790
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Quote:
Ive had my $10 cc on my 09 for four years now and its been flawless. I have the four momentary switches in a diamond pattern with ON up, SET to the left, RESUME to the right and CANCEL on the bottom. Its so easy to operate compared to the stalk mounted cc of others cars!
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Synthetic Oil: Its All In Your Head |
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11-25-2014, 10:13 PM | #10 |
Drives: 2009 5-door, 5-speed Join Date: Sep 2011
Location: White Rock BC
Posts: 687
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I would suggest clearing the codes, and then checking to see which ones come back. Some of those codes may have triggered if your key was on when the sensor was unplugged. Do not start just throwing sensors at it, as it is VERY unlikely that they are all currently bad.
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11-25-2014, 11:19 PM | #11 |
Drives: 2009 Yaris Join Date: Nov 2014
Location: Illinois
Posts: 6
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Ok disconnected all the cruise control adds, checked battery connections and left battery negative lead off for ten minutes to make sure codes are cleared. Started it up and the codes came right back. Something is a little off!
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11-27-2014, 11:23 AM | #12 |
Drives: 2008 Yaris Liftback (Sprocket) Join Date: Oct 2008
Location: San Antonio, Texas!
Posts: 2,799
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My ODB II reader gives all kinds of nonexistent codes for my Jeep. Take it to a parts place like Scott recommended...
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11-27-2014, 09:55 PM | #13 |
Drives: 2009 5-door, 5-speed Join Date: Sep 2011
Location: White Rock BC
Posts: 687
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I typed a reply the other night but it didn't go through. I think you may be seeing "History" codes. Disconnecting the battery will not clear them. If you had any of the codes you mentioned, the CEL would be on.
Clear with a proper tool and re-inspect. Cheers. |
12-06-2014, 08:46 AM | #14 |
1NZ-6spd
Drives: '05 6-Spd Vitz RS Join Date: Oct 2008
Location: Oshawa, Ontario, Canada
Posts: 2,967
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Poor Gas Mileage, No CE Light but many codes
Definitely sounds like a bad ground.
There is one cluster bolted to the side of the head on the air box side. Unbolt that and sand the head and connector and put it back together. Also sand the gound on the battery and follow that wire to where it hooks to the transmission and chassis and sand both of those too. Sent from my iPod Touch |
Tags |
mileage, obd |
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