Error code P0135?

KOOLUSA

KOOLUSA

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Dec 26, 2015
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Texas
Need some sage advice! My 2001 TJ started to have the check engine light come (and stay) on this weekend. It runs fine and no noticeable changes. I found the secret to looking up the OBDII error code with the magic turn-the-key-3x trick and got a P0135, which I just saw is a "1/1 O2 Sensor Heater Failure Oxygen sensor heater element malfunction".

This is my question. Could this error code be caused by something else (other than a failed sensor), such as bad fuel (I saw online reports of fuel with too much ethanol in it) or low outside temperatures (we just had a spell here of several days with close to freezing temperatures).

I see a lot of experience on this forum, so hopefully somebody has seen this before?
 
The O2 Sensors have a heater built in to them to shorten the amount of time it takes to bring them up to operating temperature, which allows the PCM to switch to closed-loop operation quicker, reducing emissions. The PCM monitors the voltage returned from the resistive elements and detects failure of the heater when voltage returned is not at the proper levels. The heater circuit has nothing to do with the fuel system, or the outside temperature, or anything else and will only indicate failure of the heater circuit within the sensor. Melted wiring due to contact with hot exhaust parts can also cause this error code if the heater wiring is compromised.
 
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hotolds442 said:
The O2 Sensors have a heater built in to them to shorten the amount of time it takes to bring them up to operating temperature, which allows the PCM to switch to closed-loop operation quicker, reducing emissions. The PCM monitors the voltage returned from the resistive elements and detects failure of the heater when voltage returned is not at the proper levels. The heater circuit has nothing to do with the fuel system, or the outside temperature, or anything else and will only indicate failure of the heater circuit within the sensor. Melted wiring due to contact with hot exhaust parts can also cause this error code if the heater wiring is compromised.
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X2 on melted wiring. Check those before replacing the sensor if it is melted or damaged fron the connector to the sensor replace it. Done try to repair that wire.
 
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I’m having the same issue on my 02’ which O2 sensor is this - there are three on the 4.0L right?
 
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