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The theory
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Posted by cliff Grove [Email] (more from cliff Grove) on Sun, 24 Feb 2002 20:06:22 Share Post by Email
In Reply to: o2 Sensor, PO, Sun, 24 Feb 2002 18:55:47
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The fact that you have a code for an O2 sensor fault does NOT necessarily mean that the sensor itself has failed. What the on board computer (ECM) is saying is that based on the current set of circumstances - for example -

coolant temp = 200F
air temp = 50F
throttle position = 50%
Manifold vacuum - 2 PSI
Engine RPM = 2,000
Gear = high
air flow = X cu ft min
etc. etc.

The the signal arriving from the O2 sensor should be something close to X.

and it's NOT.

I hope one of the experts can give you more definitive information, but it COULD be any one of a number of things.

1. Bad electrical connections
2. Dirty injectors (bad air/fuel ratio)
3. Manifold vacuum leak - (consistant lean mixture signal from the O2 sensor)
4. Plugged air cleaner - (Consistant RICH mixture signal from the O2 sensor)
5. Fuel Pressure regulator problem - pressure too high causes a rich mixture and the O2 sensor has to pull the system lean, pressure too low causes a LEAN mixture and the O2 sensor has to drive the mixture rich.
6. Fuel pump problem - low pressure forces the mixture lean.

Most on board systems have a different code number for O2 lean and O2 rich. Do you know which one it was?

Did you have any other indications? poor engine performance? poor gas mileage?

The point is that the O2 code only tells you there is a screwy signal (or no signal at all) arriving at the Engine Control Module from the O2 sensor. It does not necessarily mean that the sensor has failed.

I hope you get more help that I can give you.

GOOD LUCK

and please post the fix when you find it.


posted by 152.163.2...

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