o2 sensor question
#1
09-25-2008, 05:34 PM
o2 sensor question
i get a o2 heat circuit malfunction what exactly does that mean? is the sensor bad? wouldnt it idle rough or something?thanks for the info
#2
09-25-2008, 05:50 PM
RE: o2 sensor question
O2 sensors are really only accurate at high temperatures. So in order to get to closed loop faster (more efficient than open loop), they have a heating element to heat them until exhaust gets hot enough. It will work, but I imagine it will spend a little more time in open loop, until the exhaust heats them up to temp. Here is something I just found if it is still unclear.
Something else you need to know about O2 sensors is that they have to be hot (617 to 662 degrees F) to produce a voltage signal. It may take a few minutes for the exhaust to heat up the sensor, so most O2 sensors in newer vehicles have a built-in electrical heater circuit to get the sensor up to temperature as quickly as possible. These are usually three-wire and four-wire O2 sensors. The single and two-wire O2 sensors are unheated. If the heater circuit fails, it won't affect the operation of the O2 sensor once the exhaust gets hot but it will delay the computer from going into closed loop, which may cause a vehicle to fail an emissions test.
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