Causes for this code may include: Defective oxygen sensor/s Burnt, chafed, broken, or disconnected wiring and/or connectors Faulty PCM or PCM programming error

Read more at: P2238 O2 Sensor Positive Current Control Circuit Low Bank 1 Sensor 1
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Of course, it is the hardest sensor to get too! I will work on taking out the old sensor tomorrow and replace it with the working sensor from bank 2. That should tell me if the sensor is bad. By the way, it is a Denso 89467-48060.
Quick random question: why are there not that many youtube videos on first-gen highlanders? I really could not see any how-to on this subject

 

If your scanner reads real time data post the freeze frame, fuel trims, AF sensor voltage, mode 5 and mode 6 data.
I would start by checking the harness for opens, shorts, and resistance back to the ECM.

 

If your scanner reads real time data post the freeze frame, fuel trims, AF sensor voltage, mode 5 and mode 6 data.
I would start by checking the harness for opens, shorts, and resistance back to the ECM.

can you pm please?

 

hey, cr
I have Foxwell nt301. Not sure it can read real-time. How would I check the harness for open shorts?

 

Try measuring the resistance( 3-4 ohms) of the sensor internal heater circuit .
If open then needs to be changed .
This is easy than swapping. Also could be the sensor pigtail are different length and can't be swapped.

 

I have a a bias to diagnose a fault to root cause, but I have most of the equipment and background.

Truth is that if the AF sensor has more than about 100k miles on it, money and time are probably best spent just replacing the indicated sensor first as maintenance if nothing else.
If that does not fix it, then dig into (spend time and money) the diagnostics.

I decided to change my plugs, MAF and AF sensors at about 90K as a part of the major maintenance, and picked up about 2 MPG, so I saw benefit that made it worthwhile to me.

 

hi all - I did the switch. Bank 1 sensor 1 is now on bank 2 sensor 1 and bank2 sensor 1 is now at bamk1 sensor 1 and the same code pops up p22238 . So I have an open short harness (.
So the first step is diagnostics.

 

Next check the AF relay, primarily because it is easy and not because it is the most likely.

 

there are no codes pending or no codes stored. these are the best pics I can take. I will work on learning how to upload from the cell phone,
where is the AF relay located?
So as of now, the check engine light is OFF - I got excited for a moment but the smog man reminded me that I am Charly brown and said it was not ready to smog and go drive 100 miles.---fun while it lasted

 

Good news that there are no codes yet. You need to do a drive cycle to see if the monitors will reset.

 

Well after 53 miles the check engine and vcs light came back on. Along with the light these codes show on the reader
po455-po446-po441. So all these 3 codes at the same time ?

 

Go with the P0446 and the other two may not reset.

 

According to the FSM that combination of codes points to CCB stick open. I suppose it is possible that you have a cracked canister.
P0446 is a circuit code.
List of possible issues from FSM:
Vaccum hose is cracked or blocked.
Fuel cap leak
Fuel tank cracked
Open or short in sensor or valve circuit
Vapor pressure sensor,
etc.
As I indicated in an earlier post, the diagnostics are extensive. Buy the subscription to ALLDATADIY to get access to the procedure.

 

I am going to drop the gas tank first on Wednesday, And replace the check valve and gasket.
see what happens. I already replaced the solenoid on the canister. There were no cracks.

 

I would try plugging the hoses manually and pull vacuum with a Harbor Freight hand vac pump to check for leaks.

 

what a pain in the ass this was. To drop the gas tank you will need to unhook the donuts from the muffler then take unbolt the driveshaft from there you will need to unbolt all the aluminum heat shield. Then you will be able to unbolt the gas tank- its a hard reach but the check valve will come off.
Of course, I had ordered the wrong part. But besides that how do I check to see if that is working properly? I can blow into and there is no pressure at all. The wrong part has some pressure to it.
I will post a pic tomorrow the battery ran out on the camera.

ps , Don't bother with removing the rear bench seat, The carpet is glued on pretty tight, After that, there is lots styrofoam that is glued to the carpet and metal. More work that is worth .

 

On the smaller wrong part, I can blow into the tubes but it takes some pressure to blow into. on the bigger part the one I pulled off, I can blow into it with no effort.

 

If I understand what I am looking at: The FSM calls it the refueling valve: "Controls EVAP pressure from fuel tank to canister. Valve has diaphragm, spring, and restrictor. When fuel tank pressure increases, valve opens. When EVAP is purging, valve closes and restrictor prevents strong of vacuum (sic) from affecting pressure in fuel tank. When valve opens, refueling is possible."
Check that the canister filter is not plugged. It is upstream of the CCV.
I am not sure which ports you are trying to blow through, but it looks like the port in the tank should flow freely to large tube. Reverse flow should be low flow, and the small tube should be isolated from both.
It is also possible you have a bad FTP sensor.

 

well, my friends - The great news is that I passed smog today/ thank you to all.Now to Toyota engineers. the evap system needs to be placed somewhere that is easily accessible to the average jill/joe. It was a total nightmare to drop the gas tank a giant pain in the rear to get to the charcoal canister. Also, make the codes tell you what exactly the part that is no good anymore. I have a 1993 geo metro and the obd1 blinks what exactly is wrong.
And of course, on the way home I was so happy and then the maintenance required light came on. I don't think I will keep this car for long. I should get my head examined for working and spending so much money and time on this car when I could of just drive the 1993 metro.
ps the pictures is a gas check valve and that's the part that turned of the check engine light.

 

Congratulations.

 

Hey CR
I want to say a special thank you to you for always answering all my questions. hey, there are some small gremlins left / some times the moon roof does not close, the hazards lights don't work at all the clock always shows 1;00 pm or am but always 1 o'clock. Was wondering if you wanted to help/walk me through it. So if you are not sick of me and say yes-I will keep going. let me know k. Again thanks for all your help

 

Let’s keep going. I am surprised at the trouble you’ve had. But for the most part theses are good cars. Most of use like them. I agree that some of the designs are very poor for repair access. I will take a look at the hazards circuit and tell you what I think

 

You're a good guy CR thanks. I posted question already