Cleaning the oxygen sensor

jsmoke

jsmoke

jsmoke

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Can oxygen sensors go bad, in other words if your regularly getting carbon build up that triggers a fault code is it the sensor at fault or something else like a leaking seal.

Cleaning it seems to be a temp fix etc.
 
jsmoke said:
Can oxygen sensors go bad, in other words if your regularly getting carbon build up that triggers a fault code is it the sensor at fault or something else like a leaking seal.

Cleaning it seems to be a temp fix etc.
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Depending on what the contaminant is, an ultrasonic cleaner can sometimes be effective.

Anybody remember the mass fuel contamination issue some years ago?

It was a bit like Shipman and the undertakers. The first people to notice was the motor factors who suddenly found that sensors were flying off the shelves and going out of stock. Some people found that ultrasonic cleaning could provide a fix, at least for a while,

vanpeebles said:
Change it.
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In the main yes, but you do need to find out what caused the contamination in the first place to ensure that it wont just quickly happen again.
 
Oxygen sensors have a finite life, and you can't really clean them effectively as the sensing element is buried within the stainless shroud.
 
jsmoke said:
Is it simple enough to remove them and clean with carb cleaner?
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Depends which one it is and where they are on your particular car, the number 1 sensor on my old astra was easy as it was right in front of you when you popped the bonnet. Number 2 was in the exhaust so a bit more of a pain in the bum but still not particularly difficult to get to once up on stands.
 
tom_e said:
Depends which one it is and where they are on your particular car, the number 1 sensor on my old astra was easy as it was right in front of you when you popped the bonnet. Number 2 was in the exhaust so a bit more of a pain in the bum but still not particularly difficult to get to once up on stands.
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#2 sensor plays no part in the actual engine management. It is for after cat monitoring only.

However a faulty one will trigger fault codes.
 
Orionaut said:
#2 sensor plays no part in the actual engine management. It is for after cat monitoring only.

However a faulty one will trigger fault codes.
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Doesn't it? My understanding is both sensors detect oxygen levels by measuring a voltage with exhaust gasses passing over them, the ecu uses the difference in voltage between the 2 sensors to determine how much oxygen has been burnt and manages the fuelling accordingly for maximum efficiency.
 
bainbridge said:
Doesn't it? My understanding is both sensors detect oxygen levels by measuring a voltage with exhaust gasses passing over them, the ecu uses the difference in voltage between the 2 sensors to determine how much oxygen has been burnt and manages the fuelling accordingly for maximum efficiency.
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#2 sensor is not used as part of the feedback loop.

Its purpose is to monitor catalyst eficiency

A bad cat or bad sensor might generate a P0420 code. But it will have no effect on the closed loop engine fuelling

This applies to the mainstream of cars over the last 20 years or so. It may not apply to some of the most recent ones which may have more sophisticated management systems

Oh and another thing, stochiometric burns (Lambda if you like) are neither maximum power not maximum efficiency.

Maximum efficiency is achieved with lean burn.

The XJS 5.3 HE was a lean burn engine and could achieve mid 20's MPG which was pretty damn good at the time for such a large and powerful car.

ISTR that The Rover K series engine was originally developed as a lean burn Engine, But EUSSR emission rules meant that it ended up never being used to its full advantage...
 
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