Contour Enthusiasts Group Archives Forums General Troubleshooting Oxygen sensor lean codes on '95 and '96 V6 models

Having owned both a '95 and a '96 V6 Contour, I have noticed something rather interesting.

I have had the check engine light come on for a "lack of oxygen sensor switch indicates lean" on both cars.

All the times it happened (4 that I can recall), I was travelling at highway speeds of ~70MPH or more.

2 of the times that it happened, I had been driving at highway speeds for 2-3 hours or more. The other 2 times, it happened after about 20-30 minutes of highway driving.

2 of the times that it happened, it happened shortly after I accelerated onto a highway (from another highway, or from a short stop after highway driving)

I have never gotten this code during around-town, stop and go driving. It seems that only sustained high-speed driving makes it happen.

In the case of the '95, replacing the oxygen sensor made the code go away. For the '96, I have not yet replaced the oxygen sensor, and it's possible that isn't the problem, BUT the check engine light came on under the same conditions that it did on the '95, so I think it's very likely that the oxygen sensor IS the problem.

While I am on the subject, is the bank 1 (firewall side) oxygen sensor on the '96 as easy to replace as it is on the '95? On the '95 all I had to do was remove the coil pack, and use an oxygen sensor socket with a U-joint and an extension. I think there might not be enough room on the '96 for an oxygen sensor socket???

Mine is a 99 model. I never had any problems until I would drive my car to Florida. After driving on the interstate for 2-3 hours my CEL would come on. On a couple of occasions my OD off light began flashing too. Took it to the dealership. They replaced the 02 sensor and cleaned the injectors(?) By the time I got it there the transmission light had stopped flashing and they said there wasn't a problem (actually they got a code, but didn't write it down so they forgot what it was). When I had my transmission serviced, the mechanic said the fluid smelled like it had overheated, he could not find a problem. Haven't had a problem since, but I have also avoided driving on the interstate for more than 2 hours.

Very simple on a 96, took the shop 15 minutes to do on mine.
So if you know what your doing it is simple.

Currently my clunker needs a new downstrean O2 sensor, 8000 miles ago it was upstream. Hopefully this car only has two O2 sensors.

Small vacuum leaks will cause these symptoms also.

95 & 96 models will have deteriorated intake gaskets.

I'm only getting a code P1151 so I don't think it's a vacuum leak. Plus the upper intake manifold gaskets were recently replaced as part of the 99m03 recall.