Nick
06-03-2007, 08:51 PM
I've got a 1996 SR5 with low miles and decided to replace my O2 sensors before they crap out. When I was under the truck yesterday, I noticed that the rear sensor was looking VERY rusted out, to the point where a piece of the silver bit (as per photo) surrounding the sensor
http://4runners.org/image/02_sensor/02gasket_sensor_side.jpg
plain flaked off when I touched it. But then I found this bit of information:
"OBDII cars have two oxygen sensors to measure the amount of oxygen contained in the exhaust gas. The first or primary O2 sensor is located on the manifold or header and measures O2 content of the exhaust as it escapes from the cylinders. This sensor is used by the ECU to calculate fuel trims and look for combustion problems.
The secondary oxygen sensor is located after the catalytic converter and is used only to detect the performance of the converter. The ECU does NOT use any data from the secondary O2 sensor for engine management. The ECU will set an CEL (check engine light) for code P0420 if the catalytic converter is removed, the sensor is removed, or the sensor goes bad. "
So...does that mean that largely, it doesn't matter what state the rear 02 is as it won't affect my mileage, and, unless I get a CEL , I should just replace the front?
I'm new to this, sorry if it's a really basic question. College is not budget friendly and I'd rather the 90 dollars go towards something else. Thanks!
EDIT: and it looks like I should've posted this in the newbie section. doh! :hillbill:
http://4runners.org/image/02_sensor/02gasket_sensor_side.jpg
plain flaked off when I touched it. But then I found this bit of information:
"OBDII cars have two oxygen sensors to measure the amount of oxygen contained in the exhaust gas. The first or primary O2 sensor is located on the manifold or header and measures O2 content of the exhaust as it escapes from the cylinders. This sensor is used by the ECU to calculate fuel trims and look for combustion problems.
The secondary oxygen sensor is located after the catalytic converter and is used only to detect the performance of the converter. The ECU does NOT use any data from the secondary O2 sensor for engine management. The ECU will set an CEL (check engine light) for code P0420 if the catalytic converter is removed, the sensor is removed, or the sensor goes bad. "
So...does that mean that largely, it doesn't matter what state the rear 02 is as it won't affect my mileage, and, unless I get a CEL , I should just replace the front?
I'm new to this, sorry if it's a really basic question. College is not budget friendly and I'd rather the 90 dollars go towards something else. Thanks!
EDIT: and it looks like I should've posted this in the newbie section. doh! :hillbill: