Check Engine Light

[agrawalr]

Have a Toyota Avalon XL 1998.
I have a check engine light on for a couple of weeks. The light comes back on even after the EFI is removed and put back. One thing is for sure, the air filter was very dirty so I replaced it. Reset the Check Engine but came back on after a couple of trips.

Fuel Cap is tight and I never top off the fuel.

Checked the codes with Autozone code reader. The codes are P0125, P1133, P1130, P1135. Looks like the A/F, O2 sensors might be a problem. Just wondering if the dirty air filter triggered something that wont go away or needs to be cleaned up.

[thebigdog]

Mine also came on just the other day and my air filter was also very dirty so I replaced it and the light is still on do you believe it is the O2 sensor?

[garagedude]

I had check engine light on in my 2002 Avalon XLS. Researched out codes and function of A/F O2 sensors and fixed the problem. I will post below my experiences FYI, as I had posted this before (9/31) and no one has complained about it’s accuracy. Remember however it is for a 2002 Avalon – not your 1998 – but may give you some clues.

P0125 INSUFFICIENT COOLANT TEMP. FOR CLOSED LOOP FUEL CONTROL
P1133 a/f SENSOR CIRTUIT RESPONSE (Bank1, Sensor1)
P1130 A/F SENSOR CIRCUIT RANGE/PERFORMANCE (Bank1 Sensor1)
P1135 A/F FUEL SENSOR HEATER CIRCUIT RESPONSE (Bank1, Sensor1)

Fuel mixture control is combination of conditions that include O2 sensing, and temperature. Your P0125 seems to say engine is not warming up enough to operate from an open loop condition to a closed loop condition. What is you temp. gauge say? Is it below normal operating temp – could be a thermostat stuck open.
Open loop – engine runs in this mode until water temp, O2 sensor heats up enough to operate (about 1800 degrees), etc. The car computer uses a table look up method to define mixture. So this is not very accurate, and you burn more gas and possibly screw up your cat. Converter. Closed loop – it uses all of it’s sensor input to accurately define the mixture, so you should be getting about 29mpg.
The O2 sensor senses O2 in exhaust, plus there is a heater in it to bring it up to temp fast so engine runs in closed loop mode quicker. Your P1135 seems to say one of you A/F O2 sensor (heater) is bad. I had TWO bad sensors – open heater circuits - in my car at 106,000 miles, which is about when these start to fail. P1133 and P1135 is O2 response time - but may be caused by defective heater. Either way - the A/F O2 sensor is suspect. Below is my experience, and includes sensor location, how to test the heater circuit, etc. Hope this helps.
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I will post here my procedure for fixing problem with my 2002 FYI to all interested. comments/suggestions????? Part numbers for other years
may be different - you need to check.... google search for your year.
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The error code P1155 and P1135 and resulting check engine light is due to failure of one or more A/F Sensors (Air/Fuel sensor, or sometimes called Oxygen Sensor). There are three in my 2002 Avalon. There are two parts to the sensor - a heater that heats up the sensor quickly, and the Oxygen sensing part. The error code says you have a problem with the heater. Your mileage after warm up should be normal if O2 part is working OK. If you get consistent bad mileage, I would get it fixed ASAP as an over rich mixture will shorten the life of the CAT converter.
SENSOR TYPES (at least on my 2002)
Bank2 Sensor 1 - front of engine exhaust manifold
Toyota part 89467-41040 by DENSO. OEM equiv. Denso 234-9021
Heater resistance check at 68 degrees F 0.8 to 1.4 ohms
Bank 1 Sensor 1 - rear engine exhaust manifold
Toyota part 89467-41030 by DENSO. OEM Equiv. DENSO 234-9021
Cost of these about $180 each - find via google search. Toyota price
about $230 each.
Heater resistance check - same as above
Bank 1 Sensor 2 - under car in back of Catl. Converter, Connecter under
passenger front seat.
Toyota part 89465-07040 by DENSO. OEM Equiv. DENSO 234-4061
OEM part costs about $83.
heater resistance check at 68 degrees F. 11 - 16 ohms.
You need to unplug each sensor, and test resistance reading between the two terminals in sensor plug that have the two black wires into plug. This will check if the heater in the sensor is open or shorted. Resistance readings are as shown above. You will probably find one or more that have failed. I had two out of three bad!!!! (106K miles on car)
The front sensor - easy to get to and remove. The rear one - you can fish your hands down from the top by fire wall to unscrew and disconnect. The one by the cat. Converter - remove four bolts holding passenger seat, lean it back out of your way. Pull carpet out from under the plastic on the center console, pull out as best you can, you will see the sensor connector and the wires coming through the floor board. Disconnect the connector, and push the rubber grommet out the hole - then you should be able to unscrew the sensor.
You are on your own using OEM. I did but only have one day on them. This procedure is a guide only - you are on your own. One needs to be fairly mechanical to pull this off... Good luck. Hope this helps……

[gsracer]

replace tstat and gastket first clear codes andsee if comes back

[bajadog]

Try cleaning you MAF with electronic component cleaner.

It worked on my Tundra.

[1998_Avalon]

Originally Posted by bajadog

Try cleaning you MAF with electronic component cleaner.

It worked on my Tundra.

I have done this with my 96 and with my 98 Avalons. The MAF gets dirty. You can clean it with any electronic component cleaner. Just spray the cleaner down onto the two wire like components inside. Do not touch them, just spray cleaner on them. I used 99% pure alcohol on mine.

Just clean and reinstall. The Toyota dealership in Massachusetts wanted $600 to replace it. Neither one has had a problem again.

[yama6320]

i got my 2002 avalon just recently the check engine light was off the first few days and came on,
i am getting very bad gas mileage, 15 gallons giving me 200 miles local
air filter is new, any ideas what can b wrong

[garagedude]

Try to get the codes read as that will pretty much tell you where to start with this situation. It is not a good idea to continue getting such low gas mileage. These engines are finely tuned, running with that kind of mileage says that you may be burning rich which could mess up your catalytic converter - a very expensive repair.
Get the codes and let us know what they are.

[quj]

I have Avalon 01 XL, 48k. Check engine light on. code 440 446.
Dealer already changed charcoal cainster, VSV, cap. Already 4 month. 19th times come back. Every time, after one week and one day or two days, it comes again. Any idea? Help need. Thanks.

[garagedude]

quj, you might try another dealer.

[csl463]

Originally Posted by quj

I have Avalon 01 XL, 48k. Check engine light on. code 440 446.
Dealer already changed charcoal cainster, VSV, cap. Already 4 month. 19th times come back. Every time, after one week and one day or two days, it comes again. Any idea? Help need. Thanks.

My ex is having problems with her '03 - same code. Did you ever find a solution?