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Discussion Starter #1
I just got the light of death on my fj. I saw the engine light come on along with the ESP light (the car with a squiggly line). I get back to the house and hook it up to the code reader and get P0031 HO2S heater control circuit low (bank 1, sensor 1). I did some online research and I believe it's the right upstream O2 sensor. I just wanted to see if anyone else had this issue with their FJ. I was stationed in Germany where I bought the FJ. It only had 7k miles on it when I purchased it. I've had it under 2 years, bought it in 2013 and came back stateside in October. The vehicle was put in a shipping container and then on a boat for 2 months before getting to LA. The reason for the long story that seems irrelevant to my issue is the fact that being its a 2010 being bought in 2013 with so little miles had extensive rusting. I've busted numerous nuts and bolts doing minor maintenance. I'm wondering if this might have anything to do with the front sensors taking a **** on me. I also am hoping that this isn't something that is potentially going to turn into a bigger problem. She will sit until I get it figured out so I don't cause further damage. What's the standard procedure for changing the sensor? Do you typically change all of them or just the one that's bad? Any help is much appreciated.
 

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O2 sensors are pretty expencive so I would change the one that is bad and leave the rest alone :)
 

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Your not kidding on that! I found one for $90 and that's about as cheap as I'm going to get it. Thanks, I'll post an update and hope that's all that's wrong
 

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the front o2 sensors are actually called air/fuel sensors... the cheap aftermarket one are sometimes not calibrated or work good enough for what the pcm wants to see and might set a slow response code or the same code that you have. so you might end up getting the oem sensor in the long run. you might be able to find brand name in the aftermarket that will work "denso" or "ngk" but you might still end up buying oem.
 

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I just got the light of death on my fj. I saw the engine light come on along with the ESP light (the car with a squiggly line). I get back to the house and hook it up to the code reader and get P0031 HO2S heater control circuit low (bank 1, sensor 1). I did some online research and I believe it's the right upstream O2 sensor. I just wanted to see if anyone else had this issue with their FJ. I was stationed in Germany where I bought the FJ. It only had 7k miles on it when I purchased it. I've had it under 2 years, bought it in 2013 and came back stateside in October. The vehicle was put in a shipping container and then on a boat for 2 months before getting to LA. The reason for the long story that seems irrelevant to my issue is the fact that being its a 2010 being bought in 2013 with so little miles had extensive rusting. I've busted numerous nuts and bolts doing minor maintenance. I'm wondering if this might have anything to do with the front sensors taking a **** on me. I also am hoping that this isn't something that is potentially going to turn into a bigger problem. She will sit until I get it figured out so I don't cause further damage. What's the standard procedure for changing the sensor? Do you typically change all of them or just the one that's bad? Any help is much appreciated.
please let us know what repairs it... with all of your 2 posts we are skeptical!!
 

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Myfjismybaby -

The 1GR-FE engine uses four sensors in the exhaust system: two air-fuel sensors in front of the cats, and two oxygen sensors immediately behind the cats. All of these sensors need to be pretty hot to provide accurate data on the real-time air/fuel ratio. To allow the sensors to warm up as quickly as possible after a cold start, all four of them are equipped with internal heating elements.

The engine ECU (or ECM) monitors the sensor heater circuits, looking for opens, shorts, or lack of supply voltage.

Your OBD code of P0031 indicates that sensor #1 (air-fuel sensor #1 , cylinder bank #1 ) is showing an excessively low voltage in the heater circuit. The heaters themselves are usually pretty reliable, and can last 100K miles, even when the actual sensing element starts becoming sluggish or inaccurate.

This low voltage condition could be caused by an open circuit anywhere in this sensor's wiring, or an open circuit in the sensor heater itself. Given your vehicles history of corrosion problems, I would check for any corrosion at the suspect sensor's electrical connector first. Find the forward sensor on the RH exhaust system, and trace the wiring back until you find the connector. De-mate the connector (press the locking tab to allow the connector halves to separate), and look carefully for any corrosion or contamination on the electrical contacts inside the connector. Look also for any insulation damage from the wiring contacting the hot exhaust manifold, or any mechanical damage (including rodent chewing).

If you have a good quality digital multimeter, you can measure the heater resistance value between connector pins #1 and #2 ; it should be between 1.8 and 3.4 ohms. If it's outside this range, replace the sensor.



If you find the sensor heater to be open, the sensor wiring is damaged, or otherwise need to replace the sensor, USE ONLY the OEM Denso sensor. This is available from Amazon.com at significant savings from the dealer price. Go to densoproducts.com, and find the correct Denso part number for your exact vehicle. Then, order that P/N through Amazon. Make sure you get the "Direct OEM Equivalent" part number.
 

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Discussion Starter #7
Thank you for the in depth explanation. I ended up replacing the bank 1 sensor 1 and found that the old sensor was corroded. The wiring was fine but the sensor had a poor design that seemed to hold any moisture that got under the hood to that sensor. We had to go to auto zone just to get the "special tool" to get the old sensor off. But because the rental piece was slightly thicker we had to grind it down to get it to fit in the little cup that heald the sensor. Poor engineering if you as me. I didn't buy the Denso because I needed the part over nighter and Amazon didn't offer the Denso in prime and I didn't see it come with the wiring. I found a Wagner OEM direct fit, so that's what's currently installed. I took it for a long test drive and everything seems to be okay. I'll be keeping this thread going with the updates on the part to let you know if it's a good part of a fail. Any how, I will be doing a check on the other sensors just in case there are any issues as you have stated. I'm not too happy with the rust problem and wish Toyota would have the thought to carbon coat their parts to prevent rusting. If they expect it to be an off road vehicle this should have been a given. I already know this is one of many issues ahead of me.
 
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