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Discussion Starter #1 (Edited)
Hi Everyone,

Certain years of the RAV4 are notorious for illuminating the dashboard like a Christmas tree and deactivating powertrain features for something as simple as a loose gas cap.

I've had a loose gas cap once, and the computer completely panicked, throwing P0607 (PCM problem), deactivating 4WD and Traction Control...

This also happens when the computer detects problems with the oxygen sensor after the Catalytic Converter. The 2010 4-cyl engine has two sensors: the upper air-fuel ratio sensor (bank 1 sensor 1) and the lower - post-catalytic converter heated oxygen sensor (bank 1 sensor 2).




The heated oxygen sensor is located past the engine, by the passenger wheel, on the exhaust, after the catalytic converter:




I've been experiencing an intermittent P0138, especially after raining/snowing: high voltage output from heated oxygen sensor. Using a scan tool, I saw the output voltage of the oxygen sensor is stuck at 1.275V ...no matter when the engine is used (cold mornings, after highway driving, etc...)

When this code is thrown, the computer also throws P0607 (PCM failure). The 4WD and Traction control are also disabled and the respective lights illuminate on the dashboard as well.

According to the repair manual, this is likely if the OX1B and +B terminals are shorted out either inside the sensor assembly or the wiring harness/connector all the way to the computer. Here is a reference diagram of the terminals/wiring:



Take a look at my oxygen sensor below:



I measured resistance across +B and OX1B (sensor side) and got around 15 Mega Ohms...possible small short circuit...



It is my hypothesis that the crack allowed moisture and water to penetrate and short circuit the connections inside. When the weather is clear and dry, no short circuit would occur.

Anyways, I am just posting this for any future persons who might come across this issue in the future.

For my 2010 4-cyl 2AR-FE engine, the part # is 89465-0R010 Heated Oxygen Sensor. It cost $150 w/tax from the dealership.

OR, from DENSO, it is part #234-4556
 

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Your Humble Administrator
2008 RAV4 Limited V6
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Excellent detective work! One point, though, 15M ohms would hardly be considered a "short circuit", the resistance it too high. A true "short circuit" (a often misused term) would be less than 100 ohms. But I've heard some electronic techs refer to a "high resistance short" of which this is probably a good example.
 
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