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P0746 & P0776 Codes Transmission issues

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#21 ·
Bigphil555 said:
Wow, that is some work that has been carried out.

Just as a heads up, were the O2's genuine Denso ones? (Toyota OEM?). If not, copy parts will throw havoc with our Ravs. I would check this out before rechecking the ECM
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My local Toyota dealership doesn't have the oxygen sensors so I got them from the parts store (Upstream in particular is from Denso) but the downstream was another brand. I can't guarantee the genuineness of these parts since they're not coming from Toyota.

They're now suggesting we test with another valve body since we have previously tested with 3 valve bodies but shifting problems persisted
 
#23 ·
Bigphil555 said:
Worth keeping in mind on the O2, just in case.

Totally agree with swapping, to be sure, especially if it is relatively easy. Again, hope you have a known good OEM/OE one available
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OEM valve body?
Hopefully but it's most likely going to be a used part and not new from Toyota dealership. We rely mostly on imported used auto parts for aged vehicles here.
I even had to ship the ECM out for the repair and reprogramming since that service isn't available here.
So I don't even wish it to be the ECM that needs replacement entirely since that would mean I have to import one with its associated costs. I can't be sure of the used ones available here either 😪
 
#25 ·
Julius Tay said:
Can that oxygen sensor code cause shifting issues?
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I used to get codes for both upstream and downstream sensors but after replacing both recently, I only get code for upstream sensor which I replaced with a Denso Toyota branded sensor. The downstream seems to be OK now and this was rather one unknown brand.
This Rav has been great. I'm surprised things have turned this way in recent times
 
#26 ·
The O2 sensor will not cause shifting errors, I was referring to the other codes.

If you have to ship out and import parts, that makes it very difficult, so well done on sticking with it. I do not recognise the flag, where are you from?
 
#30 ·
The downstream sensor isn't as critical as the upstream since its purpose is solely to monitor the performance of the catalytic converter for emissions purposes whereas the upstream sets the air/fuel ratio of the engine.
 
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#31 ·
Dr. Dyno said:
The downstream sensor isn't as critical as the upstream since its purpose is solely to monitor the performance of the catalytic converter for emissions purposes whereas the upstream sets the air/fuel ratio of the engine.
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Oh OK wow 👌
I will surely pursue it until I get it working as required.
I'm yet to get the stock one tested on a multimeter to see if it's truly bad or the cause of the P2238 is something else. Because the sensor from outside seems to be in good shape, can't say same for the heating element.
Thanks for the clarification
 
#32 ·
Update on my 04 Rav4 with automatic shifting issues. After swapping with another valve body (4th one), I can now get all my gears shifting.
This was only achieved after a faulty electrical connection was corrected before the swap.
However, the P2238 and P2195 remain on with the MIL on.
I also came across a Toyota TSB on "MIL ON" DTC P0031 AND/OR P2238 which has to do with calibration of the ECU of 2004 year models to a current calibration ID. I'm yet to find out if the calibration has already been done on my Rav from the local dealer.
Thanks all for your advice
 
#33 ·
Thank you for the update, and well done on sticking with it.

The fact you have sorted one problem with the harness issues, and that you still have those 2 codes, I am inclined to think there is an issue on the harness with B1S1. You are totally correct in saying that part of the circuit is inside the sensor, so maybe that is where the problem lies.

Keep us updated
 
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