o/t- O2 sensor problem in car

farmalsc · Feb 15, 2010

My car (1999 nissan sentra) has an engine light on. the code is P0140 which means rear heated oxygen sensor bank 2. I have tried in the past changing the sensor but it didnt solve the problem. Should I replace it again? I clogged the tail pipe and couldnt hear a leak. Also I cant hear it when its running. Any thoughts? Id rather spend money on tractors then my car, so any help would be appreciated

Bob · Feb 15, 2010

The rear sensors have NOTHING to do with controlling the engine.

They simply "report" to the 'puter the "cleanliness" of the exhaust gases to make sure you're not ticking off the tree huggers.

The front sensors provide the actual feedback that controls the engine.

A bad injector, a cylinder "pumping oil", or a bad "cat" or something wrong with the system (if used on this model) that injects air ahead of or into the "cat" are a few of things that can make the rear sensor complain to the /puter about the content of the exhaust gases, setting the trouble code.

farmalsc · Feb 15, 2010

hey, Catalytic has been replaced. I just want the dash light off. Is it possible if i buy a controller to delete the code? I know that its the other sensor in this bank which changes my air/fuel. I just dont like seeing that oarnge glow every time i start it up. also would an exhaust leak make this light go on?

buickanddeere · Feb 15, 2010

An airleak or over active air injection pump will cause the rear O2 sensor to throw a trouble code.
The code if no longer valid should clear after approx 50 starts.

JDemaris · Feb 15, 2010

You'd better read through the Nissan service bulletins. Through 98-2000, there were many error problems associated with info the second O2 sensor was sending. Wasn't just Nissan either. Ford had a miserable time with it, and later claimed much was a software problem. An EPROM updrade supposedly fixed the problem.

supergrumpy · Feb 15, 2010

light on simply means something is out of spec, not necessarily anything close to what gave the code

have to go thru and check simple things first, if no joy you start checking expensive things, sooner or later you find what spit out the code

or go redneck and remove the light bulb

JDemaris · Feb 15, 2010

Problem is, in states like New York, all cars from model year of 1996 and newer with OBDII have to be plugged into the State computer once a year. If it sees any error codes, you are not allowed to drive the car. So, you can't just take out a light bulb - or put a piece of tape over it - like you can on 1995 and older rigs. My 92 and 95 Subarus have been taped up for years.

supergrumpy · Feb 15, 2010

didn't mean to accidently call you a redneck

in the good old days we used to run crowbar thru the cat converter when they got plugged, ran lot better

grandpappy · Feb 15, 2010

unhook the battery for 1/2 hr. then hook the battery back up an light should be out. This resets the computer.

JDemaris · Feb 15, 2010

Not at all. And if I AM one, that's fine with me. I wouldn't fix any errors if my fuel mileage didn't change. But, NY inspection forces it for anythihg 1996 and up.

My 1999 Kia Sportage has check-engine lights come on often - due to many loose and corroded wire-harness connections. When state is inspection due, I stick a code-scanner on it an hour before an erase all the errors. So far, it's worked every year.

axlehandle · Feb 15, 2010

you can by a cheep hand held from walmart

o/t- O2 sensor problem in car

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